Oliver and Slade arrive in Kasnia and meet with Nylander, one of Slade's old contacts, to get some information about his son in episode 6x05 "Deathstroke Returns".
Oliver heads to the prison in an attempt to negotiate for the release of Slade's son in episode 6x05 "Deathstroke Returns".
The team visits an expert in Vandal Savage and learn his true identity in pilot episode "Pilot, Part 1".
Stein, Sara, and Jax head to the university to borrow Stein's alpha particle tracker from his younger self in pilot episode "Pilot, Part 2".
The Legends track to the spear to the university where they find Rip Hunter shooting a movie about them with George Lucas. After Darhk and Merlyn attack the team must convince Lucas not to abandon filmmaking to save the future in episode 2x09 "Raiders of the Lost Art".
Young Ray runs through the government lab setup in an old building and ends up getting killed in episode 3x04 "Phone Home".
Zari and Ray watch the school for young Ray and later Sara searches for Ray before being attacked by the Dominator in episode 3x04 "Phone Home".
Liv spies on the Fillmore Graves mercenaries as they inject zombie blood into the vaccine supply in episode 3x13 "Looking for Mr. Goodbrain, Part 2".
Major scratches people dying at the hospital to turn them into zombies and save their lives in episode 3x13 "Looking for Mr. Goodbrain, Part 2".
Floyd Baracus is reading to a classroom of kids when Peyton gets the call about the battle at the park in episode 3x13 "Looking for Mr. Goodbrain, Part 2".
Flynn heads to an aerospace company to steal the tape needed to hack into the NASA computer systems in episode 1x08 "Space Race".
Source: What's Filming — Twitter
Flynn wakes up when Emma Whitmore walks into tell him that two more of their people left the cause in episode 1x16 "The Red Scare".