Continuity mistake: In Lucius' house, when the Doctor pulls the cloth off the shelf with the stone circuits, the position of Quintus' hand on the shaft of the torch he's holding changes between shots. (00:19:10)
Continuity mistake: When Donna changes into contemporary clothing, she has a purple shawl of sorts draped over her dress. In the first shot, she's shown with her hand out from under the cloth, but in the next shot her hand is under the cloth. (00:19:30)
Continuity mistake: When Ms. Foster's computer switches back on because it's picking up a signal from the Adiposian First Family, in a shot facing him, the Doctor reaches towards it with his left hand. In the next shot, from behind him and Donna, his left hand is resting on the wall next to the computer, before he reaches for it again. (00:39:25)
Continuity mistake: When the Doctor attempts to persuade Matron Cofelia, who is hanging in a levitation beam, to come over to the roof of the Adipose Industries building, Donna's hands, resting on the parapet on the edge of the roof, change position between shots. (00:41:15)
Continuity mistake: When the office worker gives the Doctor her phone number, he's holding the paper differently between the wide shot and the close-up. (00:04:35)
Continuity mistake: When Donna starts fiddling with the Adipose necklace she stole, this causes an Adipose to be created out of Stacey's fat cells. When this begins, Stacey is in the upstairs bathroom applying lip gloss, and she's holding the applicator wand when her stomach begins to move. When she pulls up her shirt to look at her distending stomach in the mirror, the lip gloss wand is gone. (00:07:15)
Suggested correction: Actually, it looks like she finished putting on lip gloss and put the lid with the applicator back on just before she starts feeling queasy from the impending Adipose birth.
Continuity mistake: When the Doctor is leaving Roger's house, a gadget in his pocket starts beeping. He pulls the device out with his left hand, but in a close-up of it immediately afterwards, it's in his right hand. (00:07:35)
Other mistake: When the Doctor and Donna get onto the roof, after he sonics the door shut behind them, as they run for the crane for the window washing cart he puts his sonic screwdriver in his mouth, holding it between his teeth, and pulls something out of his pocket. It looks like he might be carrying Miss Foster's sonic pen - except that at this point in the episode, it hasn't yet been revealed. (00:24:20)
Continuity mistake: When Donna attempts to smash open a window with a wrench she finds in the window washing cart, there's a shot of her and the Doctor from above where they're not in front of the window they were at in shots from inside. (00:26:00)
Revealing mistake: When the Doctor and Donna are attempting to smash open a window while stuck in the window-washing cart, there is a shot of them from above just before Foster cuts the cable in which banging sounds are heard and the cart is shaking, but if you look closely at them they aren't actually touching the window at all. (00:26:10)
The Unicorn and the Wasp - S4-E7
Continuity mistake: Thoughout the episode, Donna's rhinestone-studded hairband changes between going over or under her ears.
Continuity mistake: The house that Donna and her family are shown living in in Series 4 is different from the house the Doctor dropped her off at at the end of her first appearance, "The Runaway Bride." You would assume they'd merely moved - except that in this episode, Donna and her family are shown living in their Series 4 house before the events of "The Runaway Bride", on the day Donna gets the job that leads to her meeting the Doctor in the first place.
The End of Time: Part Two - S4-E18
Audio problem: During the climax, when the Doctor has Wilf's old service revolver and is alternately pointing it at the Master and Rassilon, there's a cocking sound every time he turns. Not only is the handgun a revolver, so it only needs to be cocked once, the Doctor is only shown actually cocking the gun once, when he first points it at Rassilon. (00:44:10 - 00:45:55)
Continuity mistake: Just before Penny Carter tells the Doctor and Donna that she's going to report them for "madness", the Doctor is seen holding Miss Foster's sonic pen, which he threw in the trash just moments earlier. (00:42:10)
The End of Time: Part Two - S4-E18
Other mistake: Shortly after everyone arrives on the Vinvocci ship, when the Vinvocci and the Doctor run through the door on their way to the flight deck, the Doctor comes back to get Wilf, who didn't initially follow because he was mesmerized by the sight of the Earth from orbit. It's obvious that David Tennant went just behind the door and paused briefly before coming back into the room, which is not what the Doctor is supposed to be doing. (00:16:00)
Continuity mistake: During the Doctor and the Master's conversation in the junkyard, the Master gets dust on the legs of his jeans. Just before he lightning-jumps away, the dust vanishes. (00:35:15)
The Sontaran Stratagem (1) - S4-E4
Continuity mistake: When Ross makes his "round the bend" pun while turning the Jeep onto Rattigan Academy's drive, the road seen doesn't match up with what's shown on the GPS display. (00:26:20)
The Unicorn and the Wasp - S4-E7
Continuity mistake: When Agatha shows the Unicorn's case of tools to everyone when they're all gathered in the parlour, the case is shown open just before she's shown opening it. (00:29:50)
Factual error: During the climax, the Moon is visible in the background, and is depicted as full. On December 24, 1851 in real life, the Moon was at first quarter phase.
Continuity mistake: On the alien ship, when the Doctor is told the bad news about the bus, his hand with the phone drops to below chest level. Then it's suddenly at chin level. (00:32:30)