Plot hole: When the newly-acquired Orac is first set up on the flight deck, Blake comments that "the other end's connected." Connected to what? Orac didn't require plugging in, other than putting his activator key in place, and that was never connected to anything else. (00:46:45)
Visible crew/equipment: At the end, when Blake says "The other end is connected," the boom shadow crosses Avon's face. (00:46:50)
Deliberate mistake: Because Stephen Greif tore an Achilles tendon playing squash, a stand-in had to complete his scene with Servalan in Ensor's underground complex. The result was a very odd segment in which we hear Travis' voice (pre-recorded by Greif) answering Servalan's lines, but never see him - except for an awkward shot of shuffling, black-booted feet that are all-too-obviously not Greif's.
Redemption - S2-E1
Revealing mistake: As Avon and the crew run through the station and the guard tosses a grenade at them, you can see the white packet of incendiary charges on the floor that will set off the grenade's explosion. (00:42:30)
Redemption - S2-E1
Deliberate mistake: In the escape scene near the end, an explosive charge that went off too soon knocked Paul Darrow over - and briefly out of the shot. Because he was able to get back up and keep running, the accident was left in, though he's said it was fortunate there was no microphone on him at the time, as he uttered a few words that were "definitely not rated PG." (00:42:30)
Visible crew/equipment: The boom shadow forms a distinct outline on the control console next to Vila when the crew are discussing Space City and the Terra Nostra. (00:04:40)
Revealing mistake: When Bek pulls the silver shroud off of Petey, note the movement on the chest of the corpse, which is obviously breathing. (00:08:30)
Other mistake: On the flight deck, when Vila says he can't remember anything "between meeting Largo and waking up back on the ship," Bek, sitting behind him, starts his next line too early, stops and waits for Vila to finish, then says it again. (00:30:30)
Continuity mistake: Cally's hair is longer & curlier in the film sequences (on the planet) than in the studio sequences (on the Liberator).
Visible crew/equipment: When the clone Blake is asking Coser for the weapon and holding his hand out, the boom mike is visible hanging over his head. (00:36:45)
Plot hole: The IMIPAK weapon marks its victims and then kills them with a secondary device. But it's inconsistently selective. When Servalan kills the guard with it, Blake and co., marked and standing nearby, are unharmed. But Rashel later warns Travis not to push the button because he and Servalan are marked and would die too. (That the weapon's range is "adjustable" is nowhere mentioned or implied. Servalan doesn't change a thing before she fires it). (00:43:55 - 00:46:30)
Continuity mistake: Jenna's bracelet changes from her right to her left wrist in mid-teleport when she and Blake go down to the planet. (00:10:00)
Continuity mistake: When the crew teleports up at the end, the shirtless Vila arrives in a completely different position relative to the others. On the surface, he's standing in a ring with the rest of them. When they materialize, he's hunched over and is now in the middle of their circle with the others around him. (00:42:25)
Revealing mistake: In the control complex, Avon tosses two coin-like objects onto the electrified floor to test the grid. But the "coin" is already on the floor before the sound effect of it landing can be heard, and the mini explosions the coins set off is the same footage both times. (00:38:30)
Revealing mistake: When Veron drops her gun in the ruined church, the noise of it hitting the floor reveals it is made of wood.
Factual error: Servalan's space station is shown rotating at a fairly fast clip. But the stars in both her office window and in the courtroom window are stationary. Because the station is spinning much faster than a planet's normal rotation, the stars should be visibly moving. (00:00:35 - 00:03:10)
Visible crew/equipment: In one shot of the Liberator's flight deck near the very end, there's a BBC workman's toolbox visible, sitting under one of the control consoles. (00:46:25)
Factual error: Avon and Vila watch the rocket launch from the surface of the planet. The rest of Liberator's crew also watch it from the flight deck, and somehow their view from orbit is at exactly the same angle from which Avon and Vila are seeing it: a ground-to-air shot. (00:03:15)