Writer/directors George Dugdale and Peter Litten later said they were both worried that working on the film might have contributed to Simon Scuddamore's suicide (Scuddamore died of an intentional drug overdose shortly after filming ended) , but at Scuddamore's funeral, his mother told Dugdale and Litten that her son had been dealing with depression and that one of his main sources of joy toward the end of his life was working on the film.
Caroline Munro, who played a high-school student in the opening scenes of the film, was 35 years old at the time of filming.
The film was shot entirely in London, England with a predominately British cast adopting American accents (with varying degrees of success) to give the impression that the film was set in the United States. In one scene, Skip (Carmine Iannaccone) tells the group that Marty (Simon Scuddamore) will have to stop terrorizing them because April Fools' Day traditionally ends at noon. If one plays a prank after noon, they are deemed the "April fool". Unbeknownst to the filmmakers, this tradition is followed in the United Kingdom but is not followed in the United States, where April Fools' Day is an all-day event.
The film's working title was "April Fool's Day", but the title was changed after Paramount Pictures acquired the name rights. April Fool's Day (1986) was released the same year.
The interior of the high school was a condemned grammar school set to be demolished. Lockers had to be added since English schools rarely have lockers, but the filmmakers were permitted to set off explosives and set the building on fire since it was scheduled to be demolished anyway. The exterior of the high school was shot at an abandoned mental asylum which has since been renovated and turned into a luxury apartment building.