The song that Gerry plays to Vanessa on the piano is Gymnopédie No. 1 composed by the French pianist Erik Satie.
Jake Gyllenhaal was originally cast in the lead role but he dropped out due to scheduling conflicts. Ryan Reynolds replaced him.
Tony Rountree, who runs the big poker game, is played by James Toback, who wrote the 1974 film 'The Gambler.' That movie was later remade in 2014 which starred Brie Larson, who would later work with Mississippi Grind directors Anna Boden and Ryan Fleck in the MCU film Captain Marvel (2019).
The scene where Curtis and Gerry are driving to Memphis and Gerry asks Curtis his age Curtis says he's 39 but Gerry doesn't believe him and tells him he's 35. Curtis admits to lying and says "I am 35." But in real life (Ryan Reynolds) playing the character of Curtis is in fact 39.