One of the actresses hired to play a cave woman misunderstood her part; she thought she was going to be modeling furs for Dr. No (1962), the first James Bond film, rather than wearing rags. When she learned she was to have some of her teeth blacked up, she left the set and never returned.
The Doctor and Susan show surprise when the TARDIS remains stuck as a police box, and Susan explains that it is supposed to change its appearance to blend in with its surroundings (an idea seriously considered by the series' creators but ruled out on grounds of cost).
The Doctor smokes a pipe before he gets captured. This is the first and last time he is ever seen smoking.
A lizard was accidentally brought on set along with the tropical plants for the forest. Carole Ann Ford took it home and kept it as a pet.
The bones used in the Cave of Skulls scenes were obtained by designer Barry Newbery from an abattoir. The smell they gave off under the hot studio lights was extremely unpleasant.