The Tale of the Big Why - S1-E8
Visible crew/equipment: When Gambit is on the wing of Turner's plane, there is a close-up of Turner where a crewmember is visible in the background.
The Tale of the Big Why - S1-E8
Revealing mistake: When Gambit is just about to shoot off Steed's door handle, the 'marble' column behind him wobbles visibly.