- Actor Allusion:
- At one point Paul (played by Dwayne Johnson) threatens a man with a bat, saying something along the lines of, "I used to use an aluminum one, but then I upgraded to wood." In Be Cool, Johnson's character Elliot is ridiculed for selecting an aluminium bat instead of a wooden one.
- When Ed Harris pretends to be a client at the gym, he says he works in "lawn and garden." He spent several years doing all of the commercial voice-overs and radio ads for Home Depot.
- Actor-Inspired Element: Rebel Wilson, an avid nunchucks user, brought her own nunchucks for the sex scene, to "spice things up."
- All-Star Cast: Mark Wahlberg, Dwayne Johnson, Anthony Mackie, Ed Harris, Tony Shalhoub, Rob Corddry, Rebel Wilson, and even Peter Stormare as One-Scene Wonder.
- The Cameo: Kurt Angle as an inmate Doyle fights with during his first incarceration. Yes indeed, it's The Rock, fresh off a WWE Championship loss at WrestleMania at the time of the film's release, versus someone who was then a mainstay of TNA.
- Creator's Oddball: Michael Bay, a director known for his over-the-top action films. directing a true-crime/dark comedy film.
- The Danza: Ed Harris plays Ed Du Bois, who is a real person involved with the story.
- Doing It for the Art: This has been a pet project of Bay's for a while, something he has been wanting to do for years but kept getting pushed to crank out more Transformers sequels (the studio rushed them out in two year intervals). All the major players, including Bay, forfeited their up-front fee in order to keep the budget down, instead getting a cut at the box office.
- Dyeing for Your Art:
- Wahlberg is no stranger to exercise or being in good shape regardless, but he really packed on muscle to convincingly portray a bodybuilder.
- As did Dwayne Johnson, who could have played the role without doing so.
- Anthony Mackie put on seventeen pounds of muscle for his role, and bulked up to 213 pounds. He had only three weeks to train before filming began.
- Hey, It's That Place!: When Adrian presents a dog to his girlfriend Robin, apartment building from Dexter can be seen in the background.
- Market-Based Title: Was released as No Pain No Gain (in English) in France.
- Name's the Same: Mark Wahlberg plays Daniel Lugo, who shares the name with an actor, according to the IMDB.
- Playing Against Type: Dwayne Johnson almost back out of the role of Doyle, not because it wasn't an interesting character to play but it was so removed from where his comfort zone was. Even as an Anti-Hero he would still have some noble and heroic qualities so playing someone who goes so far south was intimidating.
- What Could Have Been: Albert Brooks was considered for Victor Kershaw, but a deal could not be reached, and John Turturro was cast instead. Turturro dropped out due to scheduling conflicts, and Tony Shalhoub was cast.
Trivia / Pain and Gain