Continuity mistake: For one frame during the final battle with the werewolf, the logo on Batman's chest is black and white instead of black and yellow. (00:17:55)
Continuity mistake: The 10/6's on the Mad Hatter's mind control cards come and go throughout the episode.
Continuity mistake: By the time Batman gets to Ivy's garden, his cape and hood are blue, but turn to black a few seconds later.
Christmas With the Joker - S1-E38
Other mistake: Once Joker's back in his Arkham cell he should be wearing prison pants again like he was at the beginning of the episode. Yet he's still in his purple pants.
Continuity mistake: Bruce's robe goes from a light purple to mint blue while he's talking to Alfred at the end of the episode.
Character mistake: The Scarecrow's thugs flee as his water pump machine explodes, yet he seems to have stuck around long enough to be affected by his own toxin.
Continuity mistake: Both Selina's, once she's been mutated, and Tygrus' noses change color. Hers goes black briefly when she finds Batman in the forest and Tygrus' turns grey briefly as Dr Dorian scolds him.
Continuity mistake: When Clay-Face makes things like crab claws they're red. Yet later on when he fights Batman again in the TV station they're light brown.
Continuity mistake: The clay used to bind Germs goes from a creamy light brown to dark brown.
Continuity mistake: Scarecrow's boots start out dark red then they're light brown later in the episode.
I've Got Batman in My Basement - S1-E20
Other mistake: Toss a brick into a pile of empty boxes, and they won't fly around like it is shown. The heavy brick will sink into whatever hits and possibly other boxes will be affected; here the brick does not deform the box it hits and every single cardboard acts like bouncy balls. (00:13:30)
I've Got Batman in My Basement - S1-E20
Character mistake: One of the books Sherman is getting his detective stuff from is called "Crime and It's Causes." It must not be a very good book. (00:11:15)
I've Got Batman in My Basement - S1-E20
Other mistake: The Batmobile moves because Roberta is pushing the gas pedal...but one of the first shots when we see the car move, shows Roberta rolling to the back of the cockpit because of the acceleration. The car does not slow down or anything, though. (00:09:35)
I've Got Batman in My Basement - S1-E20
Other mistake: Penguin and the goons take an impossibly long time to get to Batman once he's incapacitated by the gas and is semi-unconscious at the railing. (00:07:40)
I've Got Batman in My Basement - S1-E20
Other mistake: Sherman touches by mistake the "OFF" button...which turns the conveyor belt on (there is a separate ON button...for some reason). Not just that; the buttons also look completely different between shots; first they are circular buttons with colored lights on top, then they are nondescript small levers. (00:06:55)
I've Got Batman in My Basement - S1-E20
Other mistake: The kids manage to drive away with the Batmobile simply operating the gas pedal, but they show that the gear is manual and it has three pedals.
Other mistake: The Stromwells are hugging in front of the office building, but that was the starting point 5 minutes before, there has been a long chase since. (00:21:15)
Other mistake: Batman leaps off a tall building carrying Stromwell and lands on one foot without breaking the fall. (00:12:25)
Other mistake: After the level crossing, the back of Stromwell's car is missing entirely the fender or any sort of lights. It's a close-up, even. (00:05:45)
Deliberate mistake: At Pete's diner, the owner puts the tray down, and instantly glasses appear in front of the 5 patrons. (00:02:50)
Answer: She escaped off-screen and created a copy of herself to fool everyone.