Mr. Mouse Takes a Trip is a 1940 American animated short film produced by Walt Disney Productions and released by RKO Radio Pictures. The film was directed by Clyde Geronimi and features original music by Leigh Harline and Oliver Wallace. The film was animated by Clyde Geronimi, Ken Muse, Ed Love, and Marvin Woodward. The voice cast includes Walt Disney as Mickey, Lee Millar as Pluto, and Billy Bletcher as Pete. It was the 109th short in the Mickey Mouse film series to be released, and the third for that year.

The fame of the short has since grown some historical significance, as Walt Disney himself was filmed recording his lines as Mickey Mouse for it, making it one of the only times he was shown doing his voice on camera. Alongside him as voice dubbing is actor Billy Bletcher as the voice of Pete.

The cartoon follows Mickey Mouse and his dog Pluto traveling by train, except they have a rule forbidding dogs from entering the train; Pete plays a menacing conductor intent on enforcing this rule.