|"Things were looking a little grim, but part of me was, admittedly, a little excited for a "reunion" of old friends."|
- For other uses of "Invasion!", see Invasion! (disambiguation)
- "There's Flash and—and Supergirl and—and people with actual powers now. Whatever needs to be done, they can handle it. We—we finally have a chance to be happy. I mean, why... why can't you just for a second accept that maybe this is your reward for all of the sacrifices you have made?"
"I didn't make those sacrifices for a reward, Thea. I did what I did because I thought it was right. And seeing all of this, it has just—it has shown me that there is still so much more to do, so please... I'm begging you to come with me because I cannot do it alone."
- —Thea Queen and Oliver Queen argue on their place in the alternate reality
The episode is the third of the four-part crossover, , with the eighth episode of the second season of , the eighth episode of the third season of and the seventh episode of the second season of .
Oliver wakes up to a life where he never got on The Queen's Gambit. Robert and Moira are alive and well. Laurel is his loving fiancée and their wedding is imminent. Everything seems perfect, but Oliver starts to notice small imperfections that make him question this new reality. Meanwhile, Felicity and the recruits take on a new threat with help from The Flash and Supergirl.
Oliver is seen running in the forests on the grounds of the Queen Mansion. He heads inside, where he meets and kisses Laurel, and they are about to be married. However, it is revealed that Oliver is actually living in an alternate reality, where he never became the Green Arrow, alongside Thea, John, Sara and Ray.
In the real world, at Arrowcave, Curtis, Rene and Rory are wondering, where Oliver is, when Felicity shows up along with Cisco Ramon. Cisco asks something of Oliver's in order to vibe, in order to find out, where Oliver and others are. Rene doesn't hide his disgust with meta-humans. Cisco learns, that they seem to be in some kind of alien spacecraft. Cisco hands them a piece of Dominator tech, hoping that decrypting it could provide more insight.
Inside the false reality, Oliver is seemingly living his happy life, but as he talks with others and sees his parents alive, he starts having memory flashes about his true life. Robert takes Oliver to get a tuxedo. Sara helps Laurel with moving her stuff to the mansion, but she too, gets a memory flash, when she hugs Laurel.
Back in Arrowcave, Curtis attempts to use his "3PO"-chip in order to download information on the alien device. It seems to work, but then it overheats, and device explodes. Felicity say they need a special kind of chip made for NASA, which has been stolen by dr. Laura Washington. Rene, Curtis and Rory are eager to go and get it from her, but Felicity feels they need backup, and calls for additional help.
Oliver and Robert are walking in a back alley, where Robert tries to convince Oliver to take up a job at Queen Consolidated. When Oliver looks at a building called "Smoak Technologies", he feels something isn't right. Suddenly, they are attacked by a mugger, who demands their valuables. Robert tries to calm him down, but Oliver, without hesitation, steps in front of Robert. Just as the mugger is about to shoot Oliver, an arrow appears, and Green Arrow also appears and the mugger is taken by him. Oliver has more doubts about all of this.
At the suspected location of Washington, Rene arrives late, since he didn't agree to be sped to the site with the Flash. Supergirl also drops in, but Rene disregards her. Inside the plant, Barry attempts to ask Rene about his problem, and Kara is also interested. Rene reveals that he despises meta-humans and anyone with superpowers, thinking that superpowers are bad. He goes in alone, and is attacked by Washington.
At the mansion, Oliver's memory flashes become more frequent. He leaves for the police station. In the real world Rene fights Washington and is about to be hit, when Barry speeds him out of the way. He then begins speed punching her, and leaves her disoriented for Kara. Kara and Barry do a dual-strike by Kara throwing her, and Barry making a quick punch on her. Rory and Curtis are amazed and Rene thanks the two heroes, having now seen, that not everyone with superpowers are bad.
At the police station, Oliver has a hearty talk with Quentin, and when Oliver sees a familiar sketch made from the Hood, Oliver starts to have flashes about him actually being the Green Arrow, and discovers the elevator to the Arrowcave. He goes there, and encounters Felicity, along with Green Arrow, who is John Diggle. Oliver tries to tell John about true things. John tells him to leave, which he does. In the rehearsal dinner for Laurel and Oliver's wedding, Sara meets with Ray. In this reality they never met before, but they both have flashes about their time together as Legends.
Back at the real world, Curtis dubs Washington as Cyberwoman. They get to extracting the data with the chip they pulled from her. Meanwhile, Thea is having a talk with Moira and as she hugs her, she has a flash about Moira being killed by Deathstroke. Oliver returns to Laurel the next morning. She and Sara are disappointed, since he missed the rehearsal dinner. Oliver claims he wants to marry Laurel quickly. Diggle suddenly arrives, and the two head outside. Diggle says that after Oliver left, he too has had flashes about his real life. Both come to a conclusion, that the Dominators have trapped them in some kind of false reality, and agree that they need to get out from it. But Oliver thinks that if they do, the Dominators will attempt to keep them in here. Diggle asks how, and riht after, Deathstroke appears to fight them. Oliver and John hold out, until Sara arrives and kills him, which leaves her wondering.
The three return to the mansion, and Sara at first denies the possibility, but then Oliver asks her, what is the last thing she remembers. As she thinks, she remembers how she fought Oliver under mind control, and how she, Oliver, John, Ray and Thea were taken. All three now agree that what they are seeing isn't real and agree to get out. They think the Smoak Technologies building is their way out. But first, they need to get Ray and Thea.
In the Arrowcave, all the team managed to get out from the Dominator technology is some senseless code. However, Rory says it's similar to Hebrew in Torah. Felicity decrypts it, and learns that it is giving coordinates, in negative form. Felicity realizes Oliver, Thea, John, Sara and Ray are in space, inside a Dominator Mothership.
Oliver, John and Sara go to the party, where Oliver denies all this to his parents and gives them a hearty farewell. Sara meets with Ray and Ray realizes that he is also living in false reality. Sara also tells Thea, and when Oliver comes to her, Sara leaves the two alone. Thea doesn't want to leave this reality, and Oliver is seemingly unable to convince her. He meets others outside, where they run into projections of Oliver's enemies from the past: Malcolm Merlyn, Deathstroke, Damien Darhk and H.I.V.E. members. Thea also joins after realizing she can't lose her family: Oliver. The five heroes take on the projections and defeat them. Laurel arrives, and both Sara and Oliver give her a teary goodbye, with Sara finally accepting that she can't bring Laurel back, as some things can't be fixed.
The heroes arrive at Smoak Technologies, where they find a portal. They exit, and as Oliver is about to leave, he hears his mother's voice. He turns around and sees visions of all the people he loves, with everyone saying what they said to him in the past about him being a hero. He leaves.
All five wake up inside the Domintaor ship and manage to board an alien ship to escape. As the attempt to leave, they are unable to fly the ship. The Dominators give pursuit, and things seem bad. Suddenly, the Waverider appears and throws the Dominators off and beams the heroes ship inside. Sara takes John to be fixed by Gideon and the rest go to the bridge. As Ray repeats what he heard the Dominators say, Gideon translates it and it roughly means, "The weapon is almost ready". Gideon then reveals that the Dominator Mothership is heading directly towards Earth.
- This is the first episode of the series to not feature Josh Segarra (Adrian Chase) after signing on as a series regular.
- When mentioning how they have to find "Oliver and company", Cisco makes it clear that he is not referring to the 1988 Disney film Oliver & Company that was inspired by the novel Oliver Twist.
- This is the first episode of Season 5 that doesn't include the flashback storyline.
- The beginning of the episode, when Oliver is running, is a reference to the first scene of the very first episode of (and the Arrowverse), "", a trend that continued at the start of every Arrow season's first episode except Season 5.
- This is the first appearance of Sara on since "", and the first appearance of Ray on Arrow since "".
- This episode marks Deathstroke's first appearance since "". However, he wasn't shown without his mask and didn't say a word, due to Manu Bennett not reprising the role.
- However Deathstroke can briefly be seen without his mask in Thea's flashback from "".
- Cisco refers to the stasis that the heroes are being kept in as "a little alien, a little Star Trek - J. J. Abrams style", referring to the 2009 film, Star Trek, and its 2013 sequel Star Trek Into Darkness, both of which were directed by J. J. Abrams.
- Evelyn Sharp neither appears nor is even mentioned in this episode.
- This episode marks Susanna Thompson's first appearance as Moira Queen since Season 2's "" (57 episodes ago) and Jamey Sheridan's first appearance as Robert Queen since Season 3's "" (40 episodes ago).
- In the beginning of the episode, Oliver asks Laurel, "Will you marry me?" Laurel shows him her engagement ring and responds, "I think I already answered that question." This dialogue is copied from the Season 4 episode "" from Oliver and Felicity's conversation at the end.
- The bow Cisco used to track down Oliver is the bow Oliver used in the first season.
- The Hōzen Thea gave to Oliver as a gift is the same Hōzen Oliver gave Thea after he returned from Lian Yu in "".
- This is the second episode in which Barry appears only as The Flash. The first one is "".
- When Curtis refers to his "3PO processor", before imitating C-3PO from the Star Wars franchise.
- Ra's al Ghul and Prometheus are the only main antagonists of (from the Present storyline) who didn't appear in the dream world. However, Ra's al Ghul briefly appeared in Sara's flashback from "".
- Firestorm makes a cameo in Sara's flashback from the previous part of the crossover, "". This marks the first time since "" that Firestorm appears without Martin Stein/Jefferson Jackson/Ronnie Raymond.
- Curtis claims to feel like "Elliott from E.T." before exclaiming, "It's working, it's working!", quoting the protagonist from the 1982 film, E.T. the Extra-Terrestrial.
- Ray jokingly suggests they "click [their] heels three times and say 'there's no place like home'" to escape the dream world, a reference to The Wizard of Oz.
- As the 100th episode of , this episode included clips from different episodes through the series.
- The bartender "Joe", who gives drinks to Laurel and Sara at the rehearsal dinner, is played by the real-life father of Caity Lotz.
- Laurel and Quentin are shown drinking alcohol in the dream world, indicating they never became alcoholics in that reality.
- In the dream world, Tommy was stated to be a doctor in Chicago. This is a reference to Colin Donnell's role in Chicago Med, where he plays the role of a doctor. Furthermore, this was the reason that he could not return for a full appearance. However, his image was digitally inserted during the scene where Oliver returns to the real world, much to Colin Donnell's surprise.
- Donnell posted on Twitter stating that although he did not appear, he had seen the episode weeks ago and praised the scene between Oliver and Thea and gave kudos to his Chicago Med reference.
- Felicity and Ray are revealed to be engaged in the dream world, just as they were together in the third season.
- As the heroes fight the villains in the dream world, there are throwbacks to earlier in the series, or characters gain some form of closure.
- Sara kills Damien Darhk in the same manner that he killed her sister, Laurel; thrusting an arrow into his stomach.
- Oliver kills Deathstroke, who killed his mother, by shooting an arrow into his eye, just as he did with the real Slade Wilson.
- John Diggle fights a Ghost, which is what his brother, Andy, became.
- Ray kills a member of Slade Wilson's army, who killed his fiancée, Anna Loring.
- Thea fights and kills her father, Malcolm Merlyn.
- This episode title card goes through several arrowhead designs from past seasons, from the first to the newest, as a reference to being an anniversary episode.
- After being rescued by the Waverider, Thea states, "This is exactly twice as many spaceships as I ever thought I'd be on!" Even though she referenced being on zero, she was on two spaceships, which is infinitely many more times than she imagined.
- Laurel's canary necklace in the dream world has the Black Canary's logo from the Birds of Prey in the comics.
- Oliver waking up in a world where he isn't Green Arrow is similar to episodes of , , and Batman: The Animated Series.
- In the episode, "", a Black Mercy causes Kara to wake up in a dream world where Krypton was never destroyed, and she never came to Earth and became Supergirl. Diggle even brings to Oliver's attention that he has "everything" in the dream world. This itself is a nod to the story "For the Man Who Has Everything", which was adapted as an episode of Justice League Unlimited.
- In episode, "", Barry lives in an alternate timeline he created where he stopped The Reverse Flash from killing his mother and despite having his speed, doesn't need to be The Flash.
- In the Batman: The Animated Series episode "Perchance To Dream", Bruce Wayne wakes up in a world where he is not Batman, his parents are alive, and he is engaged to Selina Kyle.
- During the scene where Laurel is getting dressed for her wedding, her hands inconsistently switch positions between shots.
Preparation ran from September 14 until September 22, 2016. Shooting ran from September 23 until October 7, 2016.
- ↑ Arrow Episode 100 “Invasion!” Description: Katie Cassidy’s Role Confirmed - GreenArrowTV
- ↑ 
- ↑ Colin Donnell (@colindonnell) - Twitter
- ↑ Colin Donnell (@colindonnell) - Twitter
- ↑ Marc Guggenheim (@mguggenheim) - Twitter
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