Plot hole: Stike implied that the self-destruct mechanism on his ship would wipe out the surrounding area, including the hacienda. But when it did go off, it only resulted in a minor explosion, too small and far away from the hacienda to do any real damage.
Plot Hole: After all the mayhem in the restaurant, the waiters and other diners can be seen in the background calmly continuing with their normal business. (On the DVD commentary, Peter Moffat claims they would have to have paid the walk-ons more for reactions).
Revealing Mistake: Just before Oscar is stabbed by Shockeye, you can see the blood pack through his thin shirt. Despite this, his fatal wound bleeds very little, not even staining the knife.
This was the late Patrick Troughton's final performance as the Doctor.
Peri: We're not going fishing, are we?
The Sixth Doctor: No. From now on, it's a healthy vegetarian diet for both of us.
The Second Doctor: Do try to keep out of my way in future, and in past, there's a good fellow. The time continuum should be big enough for both of us… just.
The Sixth Doctor: You know, I think I preferred you as an Androgum.
Shockeye: Tell me: on this planet, do they ever eat their own?
The Second Doctor: I believe in the far Indies it has been known, but I remember a dish… shepherd's pie!
Shockeye: Shepherd's pie? A shepherd? Can't we walk quicker?
The Sixth Doctor: I've come a long way for you.
The Second Doctor: Naturally. Don't expect any thanks.
Robert Holmes, this serial's writer, is a vegetarian. As such, he intended this story (particulary the parts concerning the Androgums) as a commentary on meat-eating, hunting, and butchery.
Violence corner: various stabbings by Shockeye and Jamie, and an inventive use of cyanide gas by the Doctor. There's also a tasteless gag involving a severed leg and Shockeye bites out a (prop) rat's throat. The alien chef's obsession with cooking and eating human beings as a delicacy (technically not cannibalism, but a rather fine distinction for tea-time viewing) drew unfavourable attention too.