Rod Steiger was asked by director Norman Jewison to chew gum when playing the part. He resisted at first but then grew to love the idea,and eventually went through 263 packs of gum during the shooting of the film.
Mississippi was eventually ruled out as a location due to the existing political conditions. Sparta, Illinois, was selected as the location, and the town's name in the story was changed to Sparta so that local signs would not need to be changed. The greenhouse was added to an existing home and filled with $15,000 worth of orchids.
The scene that took place at the sheriff's house featured dialog that came out of improvisations between Sidney Poitier and Rod Steiger.
The movie's line "They call me Mister Tibbs!" was voted as the #16 movie quote by the American Film Institute
The movie's line "They call me Mister Tibbs!" was voted as the #76 of "The 100 Greatest Movie Lines" by Premiere in 2007.
Virgil arrives in Sparta, and subsequently leaves town, via the old Gulf, Mobile and Ohio Railroad.
Frequently cited as Sidney Poitier's favorite of all the films he's done.
In 2007, the American Film Institute ranked this as the #75 Greatest Movie of All Time. It was the first inclusion of this film on the list.
Set in a hot Mississippi summer but filmed during Autumn in Illinois, many of the actors had to keep ice chips in their mouths (and spit them out before takes) to prevent their breath from appearing on camera during the night scenes.
The same locomotive is used in the opening and closing scenes to carry Virgil in and out of town - Gulf Mobile and Ohio locomotive #103.