"Monster" is the fifth episode of the third season of The Flash, and the fifty-first episode overall. It aired on November 1, 2016.
Desperate to understand what is happening to her, Caitlin visits her mother, Dr. Tannhauser, a renowned biomedical researcher, in the hopes that her mother can provide some answers about Caitlin's growing meta-human powers. However, when Dr. Tannhauser treats her daughter like a test subject, Caitlin grows cold and brings up past wounds causing the two to have a major blowout. Meanwhile, after a mysterious new meta-human attacks Central City, Barry tries to convince Julian to let him assist on the case.[src]
In the beginning of the episode when H.R. is handing out the coffee, he mentions that coffee from his Earth "was wiped out by blight", which is exactly what happened to coffee in the alternate universe in the sci-fi series Fringe.
H.R. mentions that on Earth-19, Hitchcock made a film titled Murder on the Titanic. In 1939, Aldred Hitchcock gave an interview to a British film journal in which he said that he hoped to make a film about the sinking of the RMS Titanic as his first Hollywood production. However, the film was never made and Rebecca became Hitchcock's first Hollywood film.
Julian mentions that he comes from a wealthy English family. This is an allusion to his most famous role as Draco Malfoy in the Harry Potter series, where the character also comes from a wealthy English family.
If that column of material was 2,000°C, Caitlin and her mother would not have been able to stand as close to it as they were without getting burned.