Mickey Mouse was the name of a popular American cartoon character.
References
Captain Jack Harkness called Mickey Smith "Mickey Mouse" when they re-encountered each other on the Dalek Crucible. (TV: Journey's End)
The Ninth Doctor, unimpressed with Disneyland and the two famous mice Mickey and Minnie, told Rose that he could take her to a place with real talking mice and ducks. (PROSE: Winner Takes All)
The Tenth Doctor jokingly introduced Martha Jones as "Martha Mouse" in Castle Extremis, to which she retaliated by introducing him as "Doctor Donald Duck". (PROSE: Martha in the Mirror) Later, he revealed to Matthew Finnegan and Emily Winter that he carried a number of watches around his pockets, one of which had a Mickey Mouse design. (COMIC: Tesseract)
One of the toy trains in the Doctor's collection was a Mickey Mouse handcar. (PROSE: Model Train Set)
Ace mentioned Mickey Mouse to Gilgamesh. (PROSE: Timewyrm: Genesys)
Trix MacMillan had a Mickey Mouse alarm clock in the TARDIS which had belonged to Anji Kapoor. (PROSE: Halflife)
Behind the scenes
- In an interview that can be found as an extra for The Three Doctors DVD, the writers wanted to name K9 "Pluto" after Mickey's famous pet sidekick, but Disney did not grant permission.