The concert was filmed at a park in Los Angeles. The scene took three days to film, and involved playing the same song over and over for all three days. To show the energy of the crowd, the extras had to cheer and "rock" to the music. On the first day everyone was up, yelling, jumping and punching their fists in the air, but by day three, most were too tired to even lift their arms, and many just remained seated.
As a cross-promotion, Warner Bros. had Robin Williams and Billy Crystal make quick guest appearances on Friends (1994), in the episode The One with the Ultimate Fighting Champion (1997).
During the filming of the concert scene, Robin Williams took a break and walked into the bleachers, where he entertained the extras who gathered around him.
Before appearing in this film, Robin Williams and Billy Crystal were already a well-known comedy duo, thanks to their work on HBO's Comic Relief. The original French film, on which this is based, The ComDads (1983), also features a well-known comedy team: Pierre Richard and Gérard Depardieu. Just the previous year, Williams and Crystal had appeared (though they shared no scenes) in Hamlet (1996), which also featured Depardieu.
While shooting the scene in which Dale and Jack remove Scott's shoes and socks, Robin Williams and Billy Crystal discovered that Charlie Hofheimer was extremely ticklish on the soles of his feet. Williams and Crystal could not resist tickling Hofheimer's bare feet, and they continually ruined the scene by tickling him. Hofheimer could not handle the tickling and wanted to quit. Ivan Reitman had to talk him into staying so that they could finally shoot the scene.