Tommy Kearins, who plays Dougie, was selected for the role after being spotted in a Scouts "Gang Show", working backstage. After being interviewed by Ealing, he spent 3 months filming on Islay. He was paid 3 times what his father made in the Clyde shipyards.
Much of the film was shot on location on the Scottish island of Islay.
The Maggie was played by two boats in the film, the Boer and the Inca.
Alexander Mackendrick was not personally very satisfied with the finished film as he felt that it concentrated too much on his own personal concerns and not enough on things relevant to anyone else.
The airplane seen when Marshall is flying over the "Maggie" is a de Havilland DH-89A Dragon Rapide, registration G-AJXB. Originally built in 1941 for the RAF as X7370, it was used for transport duty in WWII. It was sold to a civilian company in 1947. At the time of this film it was owned by BEA. Sold and re-sold many times, it flew for awhile in Sweden. It flew to Australia in 1960, where is was destroyed by an engine fire on start-up on March 30, 1968. Over 700 DH-89s of all variants were made from 1934 to 1946.