Character mistake: Upon hearing that Lister, Kryten, Cat and Rimmer have travelled from Albion - England - to India the woman in the market expresses surprise that they have travelled "halfway across the known world" just to buy lemons. In 23AD travelling from England to India was all the way across the known world. The Americas, Australasia and China were completely unknown at the time.
Character mistake: Surely, a know-all like Kryten would know that although lemons are not native to the Middle East, Babylonian traders imported lemons into what was then Judea some five hundred years before Christ was born, and by 4BC, they were quite common in the area, albeit as a pricey imported delicacy. The Dwarfers wasted half of their epic overland trek.
Continuity mistake: Rodon is revealed to be the Cat's older brother, and the rebelling cats refer to the Red Dwarf itself as the ship of their birth, but in Psirens, it was revealed that the crew spent 200 years in deep sleep while tracking Red Dwarf. This appears to have been forgotten.
Revealing mistake: After the crew transport themselves out of the book depository to escape the FBI, the astronaut helmet is transported afterwards and the two FBI agents start shooting at the box the helmet was placed on. When the box is shot, there are no bullet holes left on it.
Timeslides - S3-E5
Factual error: The newspaper detailing the bomb attack on Hitler lists the date as "Tuesday May 4 1938." May 4th, 1938 was a Wednesday. (00:09:15)
Revealing mistake: When the Polymorph, posing at the snake, jumps on Lister, it is apparent that the snake on Lister has been replaced by a plastic inflatable replica that has no features and does not move. (00:10:05)
Continuity mistake: When the Cat is eating the food set out by Lister, there is a cloth on the table. When Lister is asking where the other kitties are, the cloth is shown near the centre of the table. Rimmer then says he wants it off the ship, and the cloth is suddenly further to the right of the table. (00:27:45)
Continuity mistake: When Lister is revising for the exam, he opens a can of beer which sprays foam onto the table, and onto his cigarettes, when he opens it. A few seconds later, the sprayed foam disappears from the table. (00:19:30)
Continuity mistake: When Rimmer is talking to Lister before the exam and says they are friends, Lister replies "When?" Lister has a can of beer on the bunk, with the label facing the camera. Two shots after, the label is suddenly facing away from the camera. A couple of shots after that, the label is suddenly facing the camera again. (00:23:15)
Confidence and Paranoia - S1-E5
Continuity mistake: When Confidence is telling Lister that his song was the greatest love song ever, Lister has his right hand on his lap, but in the next shot, his right hand is suddenly on the guitar strings. (00:19:35)
Continuity mistake: When Lister is questioning how they can remake Casablanca, he is holding the video tape, but in the next shot, the tape has disappeared from his hand and is touching the control panel. (00:04:40)
Continuity mistake: When Lister is getting ready, he pulls his trousers off the table, causing the boot on the table to wobble. In the next shot, the boot is entirely still. (00:10:35)
Revealing mistake: When the Outland Revenue guy breaks Rimmer's thumb with the mallet, the mallet does not touch his thumb, but instead his fingers. (00:28:35)
Continuity mistake: When Rimmer falls asleep whilst Lister is doing the jigsaw, there is a whisky bottle on the table. Later in the episode, when being viewed on the black box, the whiskey bottle is no longer on the table. Lister could not have thrown it away since he left the table to the Hologram Simulation Suite at The End of the scene. (00:10:20 - 00:19:35)
Continuity mistake: When Lister is doing the jigsaw and Rimmer starts singing in bed, the pint mug on the table has nothing in it. Later on, when Lister returns after giving Rimmer his memory, an inch of whisky has suddenly appeared in the bottom of the mug. (00:10:20 - 00:19:35)
Stasis Leak - S2-E4
Revealing mistake: In the opening, Holly gives an additional message saying "On our journey, we have encountered many strange and bizarre things. Only last month, we can across a moon which was shaped exactly like Felicity Kendal's bottom. We flew around that one a couple of times." Before Holly says "We flew around that one a couple of times", he can be seen about to say the line, but visibly hesitates, presumably waiting for his cue. (00:01:35)
Other mistake: When Lister inadvertently sets off the Auto Destruct sequence, the computer voice says the ship will detonate in 15 minutes. The computer then says "the ship will detonate" every five seconds followed by how much time until detonation, but the time in which the computer says this is inconsistent. Two seconds after the computer says 15 minutes, the computer says the ship will detonate in 14 minutes 55 seconds. Ten seconds after saying that, the computer says the ship will detonate in 14 minutes 50 seconds. (00:01:50)
Revealing mistake: After landing on Earth, Rimmer and Kryten are standing on land. When Kryten asks "What is this place?", a car can be seen driving forwards in the far background, even though everything in this version of Earth is supposed to work backwards. (00:06:15)
Other mistake: It is established in the backwards version of Earth, that all writing is reversed and is spelled backwards. However, there are some inconsistencies, as in some instances the writing has been mirrored to appear reversed, whilst in some instances the writing has just been spelled out backwards. For example, car number plates and signs on display in the background have been mirrored to appear reversed, but the newspaper that Kryten reads, the Nodnol sign and the Sensational Reverse Brothers poster appear normally typed out, and not as the mirror image that other aspects of this world have.