Factual Error: Simply giving the men the vial of brain fluid, as the Doctor does in the end, is not going to cure them. It would have to be injected back into the cranium.
Revealing Mistake: The lever that tips the Tyrannosaur vat over can be seen.
As he is stuck on the pole the Doctor says that it was "a matter of balance". A Matter of Balance happens to be the name of a Space: 1999 episode written by The Mark of the Rani writers Pip and Jane Baker.
The Doctor: I should think you'd turn into a laburnum tree.
The Master: Laburnum? Why?
The Doctor: The pods are poisonous.
The Doctor [ to the Rani]: They should never have exiled you. They should have locked you in padded cell.
Doctor: Don't worry, Peri! The tree won't harm you!
The inclusion of George Stephenson in this episode marks the first time a historical figure has appeared in Doctor Who since Season 3's The O.K. Corral.
A refreshing lack of gratuitous violence, but the scene where the Master gets kicked in the nuts by the Rani deserves a mention because... well, just because...
Hamlet and Henry the Fourth: The Doctor quotes these Shakespeare plays with "there are more things in heaven and eart…" and "discretion is the better part of valour".