Peter Cushing supposedly only agreed to do this film if Roberta Tovey returned as his grand-daughter alongside him, having built up a rapport on the previous film.
The rebel hideout in 2150 is prominently identified as Embankment station on the London Underground's Bakerloo and Northern Lines. There had actually been a station called Embankment once, but it was renamed Charing Cross from 1915; thus Embankment was a suitable name for a fictional station. However, in 1976, 10 years after the movie was released, reality conformed to fiction when the station, now served by the Bakerloo and Northern Lines among others, was given back its original name of Embankment.
This sequel to Dr. Who and the Daleks (1965) was to have been followed by a third film, to be based on the 1965 TV story "The Chase." This was never made due to disappointing box office results of the first two films and the producers thinking that "The Chase" wouldn't have made a very good movie.
This film was part-financed by the Quaker Oats Company, then-makers of the "Sugar Puffs" cereal, in return for an exclusive merchandising deal. Quaker combined with the film team in a £50,000 campaign which included 3½ million boxes of "Sugar Puffs" advertising the film, and a competition to win toy Louis Marx Daleks or the top prize, a full-size Dalek prop. Several posters for "Sugar Puffs" cereal are visible during the movie, an early (for a British film) example of product placement. Two special screenings for grocery traders were also arranged via the deal with executive producer Joe Vegoda. The equivalent cereal in the U.S. would be Kellogg's Honey Smacks (formerly Sugar Smacks).
André Morell was offered the role of Wyler, but could not accept because he had signed to star in the four-part Doctor Who (1963) serial, "The Massacre" with William Hartnell, which clashed with the filming dates. The role of Wyler went to Andrew Keir. Coincidentally, Morell played Professor Bernard Quatermass in the original television version of Quatermass and the Pit (1958) while Keir played him in the film remake Quatermass and the Pit (1967).