Girl Trouble / School Dance - S3-E18
Continuity mistake: Besides the fact that when Helga is sharpening her pencil, the desk arrangement changes, one of the students visible when she looks at Arnold is... Helga. This happens because the shot is taken from the episode "Helga's Love Potion."
Continuity mistake: When Jennifer Walters is first introduced, her fingernails are unpolished. Later when she is restrained in Dr. Doom's lair, her fingernails alternate between being painted pink and red. Given that she and Bruce were running for their lives, she wouldn't have had time to paint her nails. Later when she transforms into She-Hulk, her fingernails turn green with the rest of her body, but if her fingernails were painted, they should still appear that color, as her skin and hair turning green wouldn't magically remove nail polish.
Deep Metal - S3-E2
Continuity mistake: Depth Charge fights Rampage on the beach. Throughout the whole episode, Depth Charge has four fingers. But in a shot when DC doubles over in pain to clutch his wounds, he has five fingers.
Star Check Unconventional - S2-E37
Continuity mistake: After the fight between Dexter and the large woman, the old Chinese woman who is sitting down has a collectible Barbie doll to the right of her in a glass case. After Dexter knocks the Barbie doll over and it breaks it cuts back to a shot of the Chinese woman and the doll is still in the case with no damage to the doll or the case.
Continuity mistake: The package Steve received from Mailbox is briefly visible before Mailbox comes in. You can also see a crew member's hand holding the package as Steve grabs it.
Continuity mistake: When Lois recovers in her apartment from the knock-out gas and starts swinging, Batman pushes her against her nightstand. But once she calms down and the camera makes a wide shot from the ceiling of the room, Lois and Batman suddenly crouch quite a distance away from the nightstand.
Mizuiro uchû ni 'Tokimeki' - S1-E4
Continuity mistake: During the 'double attack' against the robot called by Hikaru with a Gundam reference "Devil Aestivalis", her mecha is in front of Izumi's as they approach waving left and right, but when they get punched away Izumi's is the one leading the attack. (00:18:40)