Plot hole: Parker gains access to the external room using a valid security card, they figure out the CEO's passcode which opens the burn room door...and yet the room inside is still protected by a swarm of lasers. Was the CEO supposed to dance through the laser sensors like Parker does every time he goes in?
Plot hole: The car was tracked down by finding the original car key on Jimmy's body. If he had stolen the car from the original owner, how did he come to have the original car key?
Plot hole: The FBI is looking for a "very tall" guy who has been identified as such by various witnesses and by their own expert due to the entry angle of a fatal bullet wound - 6'5" at least. They send Elena into a bar near the end of the show to meet the Albanian perp who when he arrives is barely average height.
Other mistake: In the hotel room shootout, bullets are being fired through the wall easily and tearing up the place as you'd expect. Frank then dives through the damaged wall and they shoot at each other with Frank behind a cupboard and Pilgrim behind an internal wall. But bullets empties into both of these bits of flimsy cover leave the men behind them miraculously unscathed.
Character mistake: Stabler calls for an LPR check on a vehicle. The description of the vehicle he gives is for white Mazda Sentra. Mazda doesn't make a Sentra. Nissan makes the Sentra. (00:09:45)
Revealing mistake: Towards the end of the episode she picks up her phone but the screen shows the incoming call still coming through, and the screen doesn't go dark when she puts it to her ear. (00:29:30)
Character mistake: Trivette hands the man in yellow a bullet recovered from the plane Walker and Alex were traveling on, which was shot down by an assassin flying a P-51 Mustang. This man, and later Trivette, mistakenly refer to the round as a "50mm," when in reality, Mustangs were equipped with M2 Browning .50 Caliber (12.7 mm) machine guns. (00:30:25)
The Case of the Lucky Loser - S2-E2
Visible crew/equipment: After leaving her husband at train station, Harriet takes a cab to meet a man at a cabin. After a few mins, she takes the man's car to go home. As she drives away, there's a reflection of a man, in suit with glasses (possibly the director) standing offscreen. (00:05:20)
The Dog Who Knew Superman - S2-E9
Other mistake: A gangster pushes a dog into a well and the dog can be heard splashing around. The man's wife is furious and several people are unable to retrieve the dog. Superman tunnels into the ground and into the bottom of the well and emerges holding the dog. Both he and the dog are completely dry.
Continuity mistake: When James is taking pictures from a car as men are entering a hotel, in the shots of him head on he is using a Canon EOS camera with a 70-200mm white lens. In shots from the side he is using a Nikon camera with an older Nikon lens. (00:27:35)
Factual error: They used an EpiPen to bring Liv back but they're holding it backwards. The way it's being held, Ravi would have injected himself instead of Liv and she wouldn't be revived.
Continuity mistake: When Riggs is hanging from the tree, his hands are tied behind his back. When he falls and lands on his back, his hands are still behind his back. In the next shot of him, his hands are now tied in front of his body, even though he didn't have time to do anything to get his hands there.
Continuity mistake: In flashback, we see the one-armed man kill Helen Kimble by striking her with a heavy lamp. All through the earlier seasons, though, we were repeatedly told that Helen had been strangled. (00:28:50)
Factual error: The show starts in 1901 with a woman constable working for the Metropolitan Police Service (Scotland Yard). However women didn't join the Metropolitan Police until 1919 (which is also when the first woman's police uniform was created). Prior to that, women volunteered in the Women's Police Service, but that wasn't formed until 1914.
Revealing mistake: When Danny is driving Mr. Zhao in his convertible at night, you can really see that the background is a bad fake and since even though Danny is driving with the top down, his hair and clothing does not get ruffled at all by the wind.
Show & Tell - S6-E10
Continuity mistake: During a conversation with Diane, Jill says that her son is with his dad. In the conversation she calls the dad "Ken." In future episodes Jill's husband is called "Don." (00:03:55)
Thrill Kill - S5-E1
Factual error: When Dylan gets out of jail, a palm tree can be seen in the background behind him. This reveals that the scene was filmed in Los Angeles, not Philadelphia.
Continuity mistake: In the scene where Karen is about to process the sample from the bathroom the vial is in her right hand and the swab in her left. In the next shot the vial is in her left hand and the swab in her right.
Continuity mistake: When the video of Kimmy plays on the school announcements, and she talks about Duncan being hung up on Veronica, there is a cut to Duncan reacting with raised eyebrows in the foreground, while Veronica can be seen in the background with a passive expression. Then it cuts to a close-up of Veronica having a visible reaction with her whole face falling. But since Veronica and Duncan were reacting to the same thing, Veronica's reaction should have been visible in the first shot as well.
An Impossible Silence - S1-E11
Continuity mistake: When Catherine enters the precinct station, the desk sergeant places a small white file box on the counter. There's nothing else sitting next to this, but when the shot reverses, a tall black police radio with an antenna sticking up has appeared there. (00:16:10)