Visible crew/equipment: When Holly says she is broadcasting on a higher frequency, when the crew are about to commit suicide, a boom mic can be seen in the top left of the screen. (00:23:30)
Visible crew/equipment: At The End of the episode, when Kryten explains why the Cat would kill himself, a boom mic shadow can be seen moving across his face,. (00:24:55)
Visible crew/equipment: At The End of the episode when Lister makes his speech, the first shot shows a close-up of his face, then it shows a wide shot. A boom mic is pulled out of shot at the top of the screen. (00:25:50)
Factual error: While it is true that lithium carbonate can be used to treat depression and other psychiatric disorders, it cannot be administered in gaseous form. It is a very stable salt and only starts to form vapour at 1,310 degress Celcius. Spraying it about as a 'mood stabliser' at that temperature, as Kryten does, is going to kill everyone on the spot.
Revealing mistake: In several episodes, but mostly in series 6, we see lots of profile camera shots of just Lister and The Cat at the front of the cockpit in Starbug. Quite a few times you will see Lister mouth The Cat's lines so he knows when to start speaking and what to say.
Revealing mistake: As Lister tries to sharpen/shorten his nails after getting out of deep sleep, you will see just before he stops that one nail snaps at the finger. He continues as if nothing happens, holding his hand still, as if it was still in the sharpener. (00:02:00)
Other mistake: Kryten places Rimmer's light bee on the floor, then begins the process of reinitialising him. As the process finishes and Rimmer looks at Lister (who looks away), the light bee, which should be hovering within his torso projecting his image, is still visible on the floor between his feet. (00:06:00)
Continuity mistake: When Lister is watching the video message of a psiren, posing as Kochanski, Lister asks "How? I don't understand" and Kochanski, on the video appears to move her face beginning to reply, but when the shot cuts back to the video, Kochanski's face is suddenly still. (00:16:20)
Revealing mistake: Just after we see the first meteorite, there is a brief moment where the model shot and the crew walking into the cockpit overlap causing both images to be seen together. (00:16:55)
Revealing mistake: When Starbug gets hit by the meteorite, the word 'Starbug' on the ship is backwards revealing the film has been mirrored. (00:18:25)
Revealing mistake: The spike that kills Pete Tranter's sister is visible before she reacts to it, just below her elbow. (00:21:20)
Revealing mistake: During the 'Two Listers' scene, specifically the cut when Kryten tosses the apples to the Listers, the split screen is quite visibly moving in between the chairs. (00:22:55)
Answer: It's Queen Victoria, someone any Englishman would recognize, and needed no introduction.