Among the homeless men whose photos were taken by the David Hemmings character is Julio Cortázar, who wrote the original short story on which "Blow-Up (1966)" is based.

The film contains a rare performance of The Yardbirds during the period when Jimmy Page and Jeff Beck were both in the band. Jeff Beck would leave a few months later.

Sir Sean Connery turned down the lead role, because, "I couldn't understand what Antonioni was talking about."

As a way of bypassing the Production Code (i.e. censors), "MGM" created "Premiere Productions". This was a dummy company which had no agreement or affiliation with the Production Code and, therefore, did not have to adhere to its standards. "MGM" did not have to cut the full frontal nudity or other sexually explicit scenes and maintained all rights to the film. When the film opened to rave reviews and excellent box office, this defeat was considered the final blow for the Production Code's credibility and was replaced with a ratings system less than two years later. Because the film did not open with a studio logo, the version shown on Turner Classic Movies has a Warner Bros. logo at the start, it being the current owner of the film.

According to Don McCullin in his autobiography "Unreasonable Behaviour", director Michelangelo Antonioni was unhappy with the color of the grass in Maryon Park. He had it sprayed green so he could re-shoot the scene.