Trey Parker and Matt Stone agreed to do this film under the assumption by the time filming began, South Park (1997) would have already been canceled. It wasn't, and having been committed to both projects, had to attend principal photography for this project during the day, and produce South Park (1997) during the night, leaving very little time for any sleep.
The movie is based on a real-life game that director 'David Zucker' created with his friends, literally played in the driveway of his home. Many of the reappearing teammates are friends of Zucker and actual original players of the Zucker-driveway game, asked by the director to be in the movie to pay homage to origins of BASEketball.
The role of Kenny "Squeak" Scolari (Dian Bachar) was created when Trey Parker and Matt Stone were cast. Director 'David Zucker' had no intentions of a third character, but Trey and Matt convinced him to create the part.
In the scene where Remer meets with his entertainment lawyer, Coop accuses of Remer of being a "sell-out" for doing "a big Hollywood movie" now that he's famous, leading to Coop and Remer to act as though they'd heard that phrase before. This is a reference to the fact that, when BASEketball was announced, many of South Park's fans accused Matt Stone and Trey Parker of being "sell-outs" for doing "a big Hollywood movie" now that they're famous.
The internet slang for stupidity, the expression 'derp' was first used as a line in this film by Matt Stone's character. The term is later used in a number of episodes of South Park (1997)_ by Matt Stone and Trey Parker, that led to the spread and usage of the term.
During the "Unsolved Mysteries" scene, almost all of the computer users in the background behind Robert Stack are playing solitaire, Except the one to the far right that is playing the classic point-and-click adventure game Myst by Cyan.
The celebration salute that Remer, Coop, and Squeak do after the Beers win the Denslow Cup is the same salute that the NFL team the Denver Broncos did as a touchdown celebration at the time. This was known as the "Mile High Salute". Matt Stone and Trey Parker are avid Denver Broncos fans.
In the final game, when trying to "psych-out" a fat Dallas player by commenting on his weight, Trey Parker's character Joe Cooper begins to speak in a high pitch, "whiny" voice reminiscent of Eric Cartman, another character from South Park (1997).
The scene where Joey asks Coop to hit a home run for him on the night of his liver operation is inspired by a real life event in which Babe Ruth visited a sick child in the hospital and promised to hit two home runs for him.
During the hospital scene where Coop and Remer are "attempting" to bring little Joey back to life, Coop requests heart paddles, calling them "the little things George Clooney uses." This is a reference to when Clooney was on E.R. (1994). Clooney would later cameo as Dr. Gouache in South Park: Bigger, Longer and Uncut (1999) and as Sparky the dog in the South Park television series.