Continuity mistake: Stromwell crushes under his fist the remote control - not bad for a supposed old man! But the remote is also completely gone in the next shot. (00:02:10)
Continuity mistake: There's a marked cone of light on the door that leads to Harvey's room inside club Wild Deuce; it disappears after the opening shot. (00:15:05)
Continuity mistake: When Batman drives his two-wheeled vehicle out of the Batcave, there are no numbers on the concrete as they appeared in 1x8.
Continuity mistake: Harvey Dent's mud stain is different when he looks in disbelief after Thorne's goon says he'll chew and spit him. He's got a stain on his lapel that was never there before and is gone later. (00:04:55)
Be A Clown - S1-E11
Continuity mistake: Joker splats a full cream pie on the mayor's face. When he walks away, the screen has mostly cleaned itself. (00:03:40)
Be A Clown - S1-E11
Continuity mistake: The Mayor is giving an inauguration speech. Look at the crowd in the long shot. It cuts closer, and you can see that the man in cowboy hat that was in the crowd moved behind the mayor on stage. A journalist in red tailleur also switches to lilac. (00:01:20)
Continuity mistake: Alfred is skilfully dancing while sitting and sipping tea. The radio rests next to a circular monitor on the computer. Then on a featureless spot, then directly on the monitor itself. (00:04:05)
Continuity mistake: When Batman cuts off the first tentacle, the liquid is clear. Further slashes reveal the 'blood' of the creature as being green-ish. (00:18:40)
Continuity mistake: Batman breaks a few teeth of the monstrous venus flytrap-like plant, but it has a mouth still full of teeth in the rest of the episode. Similar fate befalls Batman's cape. (00:16:20)
Continuity mistake: When she says "Mm, a little big for a fly" at the sight of Batman, Poison Ivy is wearing her boots and bodice, but her legs are bare. In the rest of the episode she is wearing green stockings. (00:16:15)
Continuity mistake: Harvey Dent is brought inside the hospital on the stretcher fully dressed in his business suit. Which is pristine clean, despite the face he just facemoussed and got chocolate splatters all over himself. (00:08:40)
Continuity mistake: Captain Clown gets pressed into a block of scrap metal. The ascot faces the front side (the one facing the direction the conveyor belt carries it to) in the first shot, then Joker dumps more junk on Batman and goes away sitting on the block; the ascot is facing now the back. (00:17:15)
Continuity mistake: The boat with the gas-emitting garbage goes past the bridge, and its odor approaches the bridge trailing behind, from the left of the screen. A few seconds later it also intoxicates the street workers, but the miasma approaches from the right. (00:02:00)
Continuity mistake: Batman knocks the tommy gun off Anthony's hand. He is looking at the weapon that lies on the blimp, and then tries to seize it again. The weapon is positioned different between the two shots. (00:15:25)
Continuity mistake: Batman is analyzing Scarecrow's mask at the computer. During the whole scene the photo of his parents and the newspaper change position. (00:10:20)
Continuity mistake: Scarecrow just terrorized the security guard. His two goons approach him asking what did he do. The one with the grey coat has his Tommy gun in his right hand, the one with the brown coat keeps it off frame. In the second they are off camera, grey coat switched hands to the gun, and brown coat is holding his to his chest. (00:04:20)
Continuity mistake: A security guard is recording a silly audition tape-like message. His shadow reaches barely the bottom of the wall, then it's suddenly almost mid-height on it. (00:02:30)
I've Got Batman in My Basement - S1-E20
Continuity mistake: Sherman hangs the two front pages overlapping in close-up, at distance in the next shot. (00:21:15)
Answer: She escaped off-screen and created a copy of herself to fool everyone.