Other mistake: The episode's action takes place around 11:00pm (night time), yet all the scenes show broad daylight.
Other mistake: During the scenes of the invasion of Normandy, stock footage of U.S. Marines, Marine landing craft, Marine tanks, etc., conducting landings in the Pacific theater is used.
Surf's Up! Joker's Under! - S3-E10
Other mistake: An amazingly precognizant Dick Grayson is already wearing his surfing togs before Commissioner Gordon calls to say that Joker has invaded the surfing community. (00:04:30)
Suggested correction: Dick isn't amazingly precognizant. He's wearing swim trunks while using the rag to prep his own surfboard. Barbara Gordon was already at the beach with Skip, and Dick is heading to the beach with his surfboard as well (00:04:34).