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.
Other mistake: The Cat Priest has no fangs when every other Felis Sapiens has them.
Other mistake: Holograms are often seen passing through physical objects, walls, furniture, and other people. Yet, they have a physical object generating the hologram: their light-bee. This would not be able to pass through other solid objects.
Continuity mistake: When Rimmer is about to tell Lister how many times he made love, Lister tells him that he'll "wake up in the morning with a hangover." But Rimmer and Lister already have fallen asleep and woken up, and they have the hangovers right now.
Answer: It's Queen Victoria, someone any Englishman would recognize, and needed no introduction.