The idea for Crashing originated from a comedy sketch Holmes and Apatow filmed for a February 2014 episode of Holmes's talk show The Pete Holmes Show, in which Holmes pitched a story based on his own life about a religious man whose wife cheats on him, to which Apatow initially responded that it seemed 'tragic and sad' rather than comedic.

Holmes only saw the potential of his life story as a show premise after his friend, actor Brian Sacca, suggested adapting it into a one-person show for Holmes to perform.

Holmes pitched the concept to Apatow during a single-day trip to New York City, catching him during a break in filming Trainwreck (2015); Apatow then asked Holmes to write ten pages of personal life events, which Holmes filled with 'truly embarrassing admissions and sad things.'

Artie Lange originally auditioned for a minor, entirely different character with only two lines, but after Apatow told him to forget the script and improvise based on stories from his memoir Too Fat to Fish, the character evolved into a scripted version of Lange himself.

Holmes credited Apatow entirely for casting decisions on Artie Lange, Gina Gershon, and Lauren Lapkus, calling it a 'brilliant stroke of casting'; Gershon reportedly didn't even have a formal audition since Apatow simply decided she should play the role.

For scenes at real comedy venues, Apatow had Holmes perform his early stand-up material four or five times to a crowd of extras so they would react naturally, creating the impression that Pete was bombing on stage.

A pizza shop scene between Holmes and Lange was originally scripted but Apatow scrapped it in favor of having Lange improvise advice for a new comedian; Holmes considers this improvised scene the one that clinched the series deal with HBO.

Scenes in the first two episodes were shot in Artie Lange's real-life apartment in Hoboken, New Jersey, and the sixth episode recreates Holmes appearing on Lange's real podcast, which Holmes had actually guested on in November 2015.

Artie Lange was paid $15,000 per episode in season one and $17,500 per episode in season two; his real-life arrest for cocaine and heroin possession in March 2017 led to public speculation he had been fired, though Apatow publicly denied this and confirmed his continued involvement.