* CaliforniaDoubling: Set in England, filmed in Toronto, for tax reasons.
* DawsonCasting: Frequently done with regards to 17-year-old Alan for understandable reasons. Creator/PeterFirth, the originator of the role, was 19 (and thus a legal adult) when he began playing the role on the London stage in 1973, and continued until he turned twenty-three years old during the filming of the screen adaptation (released in 1977). Averted by the 2007 West End revival (you know, the one that got the MoralGuardians up in arms); Creator/DanielRadcliffe (born in July 1989) actually was 17 when the production opened in spring 2007, though he had already turned 19 when the show's Broadway run started the following year.
* SerendipityWritesThePlot: In the film adaptation, censors made very clear that Peter Firth could not be shown to have an erection, which happened to work very well for the scene when Alan is trying to have sex with his girlfriend and can't get it up. Throughout the scene Alan's lack of interest in Jill is visually obvious to the viewer, but both characters studiously ignore this fact until it becomes impossible for them to continue.

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