Remembrance of the Daleks - S25-E1
Factual error: The events depicted are supposed to have taken place at the time of the broadcast of the first Doctor Who story... Saturday 23rd November 1963 at 5:15pm. However, the non-wintry weather and the bright evenings don't fit late November/early December.
Remembrance of the Daleks - S25-E1
Visible crew/equipment: At the beginning of the episode when the soldier is thrown back after being exterminated, the wire pulling him is very visible.
Remembrance of the Daleks - S25-E1
Continuity mistake: After the Special Weapons Dalek blows up the gate to Ratcliffe's warehouse, you can see that some of The Daleks were slightly damaged by the explosion. In all the following shots, they have been repaired.
Remembrance of the Daleks - S25-E1
Character mistake: The gate to I.M. Foreman's scrapyard reads "I.M. Forman."
Remembrance of the Daleks - S25-E1
Revealing mistake: When the Doctor slides with his umbrella from Coal Hill School to the Dalek spaceship, he is obviously not played by Sylvester McCoy. He is much too tall.
Remembrance of the Daleks - S25-E1
Continuity mistake: When the Doctor and Ace steal the military van they leave the doors open, but in the next shot when we see the van leaving Totters Lane the doors are suddenly closed.
Remembrance of the Daleks - S25-E1
Other mistake: Right before the Doctor gets attacked by the destroyed Dalek he says: "Let me see, Professor" but the subtitles says: "That's impressive."
Revealing mistake: When Ace and Susan are sitting underneath the huge pipe about to be executed by the Fondant surprise, it's obvious that the actresses aren't sitting directly underneath the pipe, but slightly behind it.
Revealing mistake: In episode one, as the Doctor is repairing the buggy, one of the patrol runs on too soon, realises that he's come in ahead of his 'cue', and runs back.
Audio problem: In episode 2, the Kandyman's microphone picks up quite a bit of the Doctor's dialogue by accident.
Revealing mistake: When the Doctor taps the ice crystals, they wobble instead of breaking.
Plot hole: In episode 1, on both occasions that Silas P presents his card (first to Daphne S, then later to the Doctor), he gives it to his victims the wrong way around. They have to surreptitiously turn it over so that the side with his name on it is facing them, and then act surprised when he tells them to flip the card over to reveal the words "Happiness Patrol Undercover", as if they hadn't seen it before.
Continuity mistake: In the scenes set in the underground tunnels in Part Three, the Kandy Man has no metal brace around his mouth, but he does have the brace in other scenes.
Factual error: In 1638, a mathematician calculates that the asteroid will return in 350 years time, on the 23rd of November 1988. But in 1752, Britain's calendar was moved forward 11 days so that it matched with that of the Vatican. This means the asteroid would return on 4th December, so everything that is supposed to happen in this story after 1752 is 11 days out.
Battlefield - S26-E1
Deliberate mistake: Look for the "creases" in the wall inside the TARDIS, which look as if the wall was just a sheet hung up behind the console. (In fact it actually WAS a sheet and not a "solid" wall - the TARDIS wall prop was apparently unusable due to water damage, due to poor storage between seasons. This also explains the lack of TARDIS interior scenes throughout the rest of season 26: it was not thought worth repairing the TARDIS set [or building a new one] when the show was in imminent danger of being cancelled after season 26).
Battlefield - S26-E1
Continuity mistake: When the roof falls on Ace and Shou Yuing, Ace's face gets covered in dark streaks, which mysteriously disappear soon afterwards.
Battlefield - S26-E1
Character mistake: The Brigadier asks the pilot if she speaks Czechoslovakian, even though Czech and Slovak are different languages.
Plot hole: A line of dialogue in "The Curse of Fenric" indicates that the Russians planned to make their escape by "going to the North Way", in other words, escaping to Norway. However, the story is set in the summer of 1943, when Norway was under Nazi occupation. It would not be a smart idea for any Russian military personnel to head for Nazi-occupied Norway.
Factual error: The story is set in 1943. Jean and Phyllis shouldn't readily know who Jane Russell is, as she didn't become famous until her debut film The Outlaw was a box-office hit after the war, three years later. (Although The Outlaw originally had a limited release in the US [but not the UK] in 1943, it was quickly withdrawn by the censors and not released widely until 1946.) True, they could have read about this film in a newspaper or magazine, but considering the strict wartime censorship then in force, it is unlikely.
Revealing mistake: When Ace is being attacked by the Haemovores, she strikes one of them on the head, causing its mask to go up and revealing part of the actor's neck.
Chosen answer: The Master is insane. If he can't control the universe, he'd rather see it destroyed.
Captain Defenestrator