Justice League (2001)

Paradise Lost (2) - S1-E9

Continuity mistake: When Flash plays tag with Faust ("Now you see me, now you don't"), there is a brief shot in which he rushes at Faust - but not inside Hyppolita's palace, but in some high-tech laboratory. Obviously a shot from some earlier series, since the coloring and style are different from the Justice League's.

Starcrossed: Part III - S2-E26

Continuity mistake: The surveillance video of Hawkgirl talking to the Justice League is different than what we saw in the previous episode. She doesn't move towards Bruce in the video, people are in different positions, and Clark has glasses on in the video.

Injustice For All (1) - S1-E18

Continuity mistake: When Trina runs to her dad, he gets down on two knees. In the next shot, when Superman and Flash arrive, he is seen kneeling on three legs.

Paradise Lost (2) - S1-E9

Continuity mistake: When Joker comes down to the basement to kill Batman, he finds the empty titanium restraints still fixed on the post. But when Batman gives him the knock-out punch, the restraints have suddenly disappeared.