Board Thread:Arrow discussions/@comment-807326-20170525002354/@comment-25449165-20170525044815

Teddybearlover wrote: awesome episode. we don't really know if everybody on the island is dead. we have to wait for season 6. William knows Oliver is his dad.

Correct me if I'm wrong, but I think he knew Oliver was his father the moment he was kidnapped by Damien Darhk. It's just he never knew his father was the Green Arrow until now, and Oliver planned on revealing this secret to him on William's 18th birthday. (That video he filmed).