Revealing Mistake: When the camera zooms in on Tlotoxl as he prepares the sacrifice, it hits the latter and jerks.
Equipment Visible: In the very first shot of the episode, the shadow of the camera moves over the remains of Yetaxa.
Barbara: Oh, don't you see? If I could start the destruction of everything that's evil here... then everything that is good would survive when Cortez lands.
The Doctor: But you can't rewrite history! Not one line!
Susan: Barbara, the high priest is coming.
The Doctor: Barbara, one last appeal: what you are trying to do is utterly impossible! I know, believe me, I know!
Barbara: Not Barbara, Yetaxa.
Novelisation: Doctor Who: The Aztecs by John Lucarotti (ISBN 0 426 19588 4) first published by W H Allen in 1984.
DVD: Doctor Who: The Aztecs (BBCDVD 1099) released in August 2002 (Region 4 in December 2002). Released in U.S.A./Canada (Warner Home Video E1719) in March 2003.
a commentary by producer Verity Lambert and actors William Russell and Carole Ann Ford;
"Remembering the Aztecs" - interviews with guest stars John Ringham, Walter Randall and Ian Cullen;
"Designing the Aztecs" - an interview with set designer Barry Newbery;
"The Story of Cortez and Montezuma" taken from Blue Peter broadcast on 21/09/1970 and presented by Valerie Singleton;
"Restoring the Aztecs" - a look at the process of restoration for this story;
Arabic soundtrack for episode four;
"Making Cocoa" - an animated short about the Aztec process of making cocoa;
Video: Doctor Who: The Aztecs (BBCV 4743) released in November 1992. Released in U.S.A./Canada (Warner Home Video E1257) in May 1994. The "Next Episode" caption has been deleted from The Day of Darkness.