The Hold Up - S10-E3
Plot hole: When the robbers come onto the floor and go into Mr. Rumbold's office, the staff suggests calling the police, only to be told by Mr. Harman that the only outside line is in Rumbold's office. This, despite the fact that there have been numerous occasions throughout the series where characters made and received personal calls on the department phones (Mrs. Slocombe calling her cat, Mr. Humphries calling his mother, etc).
Mac is a Serial Killer - S3-E10
Plot hole: Early in the episode, it is mentioned that the serial killer is murdering "Young, attractive blondes", yet at the end of the episode, when the gang finds all the severed heads in the killer's refrigerator, almost none of them are blonde or young, contradicting what had been previously established.
Plot hole: Kenan ends up out of the door when trying to persuade the robbers not to give. Surely with all the media attention, a camera would have spotted him, and his family would realise it's Kenan. (00:20:30)
Plot hole: The bedroom scene finds Robert sitting up in bed after getting home from the hospital with his upper thigh injury. If he really had a wound in that spot, there's no way he could sit like that.
Plot hole: When Justin and Juliet were trapped behind the glass and Juliet let herself be captured by the mummy, so she doesn't burn to ashes when the morning comes, why didn't Juliet just escape? The mummy gave her enough time to turn around and share a moment with Justin, she could've used that time to fight him off, break Justin out and escape. The mummy wasn't very strong and Alex would've shown up 20 seconds later anyway, there wasn't any real reason for Juliet to just let herself be taken away.
Plot hole: In Blakey's office Stan shows Blakey the toy bus he has just brought for his nephew. How can Stan have a nephew when he isn't married and his only sibling is his sister Olive, who doesn't have any children?
Oops!...I Did It Again - S2-E22
Plot hole: Lily was vomiting because of the antibiotics she was taking for the infected tattoo. But initially, Sean and Claudia were both puzzled by her being sick. As a teenager, how could she have seen a doctor and been prescribed medicine without a parent knowing?
Plot hole: Amy lets Scully place the witch in the break-room, but how could she have known that after captain Holt steals the crown out of the locker, he would go there? And not for example goes back through the window he came from.
Plot hole: In this episode, a very star-struck Paul meets Jerry Seinfeld on the street. It's not clear whether Jerry is playing himself or his Seinfeld character, but either way it's a mistake. If Jerry was playing himself, it's a mistake because Mad About You did a crossover episode with Seinfeld in its first season, so it would be impossible for Seinfeld (the TV show) or Jerry Seinfeld the actor to exist in the Mad About You universe. If Jerry was playing his character, it's a mistake because it was established in that crossover that Paul and Jerry used to be neighbors and knew each other fairly well, so Paul wouldn't be at all star-struck.
Plot hole: During the episode "Superstition", Onizuka thinks he has cancer because the magnetic pain-pads he was wearing created strange blobs in the X-Ray he has taken. However, given the fact that the X-Ray was so strange, doctors would have given him a complete physical, and noticed the pads much sooner. Here, they literally just assume he has tumors, and fail to ever take notice of the pads. Simply impossible, given the gravity of the situation. (Obviously, this is to pay off at the very end of the episode.)
Plot hole: Someone as careful and controlling as Timo would never force anyone into working for him, for exactly this reason.
Deathfist 5: Major Crimes Unit - S2-E15
Plot hole: The whole case is solved because of astronomical coincidences, since the culprit is someone related to the actor, who is teaming up with the investigators for an entirely unrelated reason. Los Angeles is kinda too big for this sort of 'coincidence'. Moreover, had they committed the crime any other day (there was no particular reason) there would have been no connection.
Plot hole: In "The Conners" premier, Dan solely blames neighbor Marcy Bellinger for Roseanne's death after finding a bottle of opiates with Marcy's name on it. He only relents after Darlene shows him additional opiates that other people gave Roseanne and were hidden around the house. However, in the Season 10 reboot of "Roseanne", Dan had previously discovered and confronted Roseanne about her multiple opiate stashes, including one bottle with Marcy's name on it which he read aloud.
Plot hole: In Russia, Soldier Boy is shown heading to the airport, He wanted to get to the US and start his revenge against his team. Problem is: he has no documentation and money to take a flight. Even if he stole the money somewhere, still would be impossible to travel without the proper documents.
Plot hole: In the pilot Jimmy finds out Lucy is pregnant while visiting her cell. In S2 E21 (Inside Probe) he finds out while taking to Lucy on the prison phone.
The Muh-Muh-Muh-Murder - S1-E25
Plot hole: Daffy isn't able to escape Porky's house until he gets the keys, but later it is revealed that the reason he couldn't get out was because he was too weak to open the door. If that was the case, the keys shouldn't have been able to help him get out.
Plot hole: Kings Boomer and Brady had to earn their king rings and the powers contained within, however, King Boz was just handed the ring, yet it kept its power.
Plot hole: The bad guy somehow knows what is going to happen (via the sketches) even though the events haven't happened yet, like knowing Mrs Peel was going to show up at Pool's mansion in that catsuit and hat, and that the scenes were going to play out like the sketches.