It took 4 hours to put the 12-pound "face" on Ryan Reynolds. When Reynolds stepped outside in full fat make-up, a fan of his came up to him and asked if Ryan Reynolds was inside. He said yes and pretended he wasn't himself.
Since the movie was filmed in Canada, many of the minor characters (as well as lead actor Ryan Reynolds) are played by Canadians. Three of the supporting actors - "Fred Ewanuick", "Mike O'Brien" and "Cavan Cunningham" were regulars on the Canadian sitcom "Corner Gas".
Ashley Scott who played Janice, the nurse Dusty was singing to at the medical center, and star Ryan Reynolds have both played DC Comics superheroes. Scott as Helena Kyle/Huntress in Birds of Prey and Reynolds as Hal Jordan/Green Lantern and Deadpool.
In the theatrical trailer three women, Susan Ward, Mircea Monroe, and Natassia Malthe are featured displaying Chris Brander's bachelor lifestyle. This scene was in the original ending that was ultimately cut from the film. The original ending can be seen on the DVD in its entirety as a bonus feature. The same actresses also make a second appearance in the "Jamie Smiles" music video, which is also included on the DVD.
The trivia item below may give away important plot points.
On the DVD an alternate ending was included as bonus material. The alternate scene takes place before Chris's return to New Jersey for his reconciliation with Jamie. After the fight with Jamie, Chris returns to California to find that Samantha has become a more accomplished song writer by writing a new 10 tracked album, being hailed, by Chris's boss KC, as an instant hit. The new songs on said album are based on their recent tumultuous visit to New Jersey. Meanwhile Chris falls back into old habits and attempts to forget about Jamie by spending time with 3 L.A. party girls, played by Mircea Monroe, Susan Ward, and Natassia Malthe, who inexplicably were staying at his home while he was away. Unfortunately in an attempt to elevate the mood by playing music they find a demo of Dusty Dinkleman's in Chris's travel bag, which triggers Chris's emotional spiral and a subsequent retelling of the events of the past few days. The girls attempt to comfort Chris, but to no avail. As the scene ends Chris has a look of longing on his face. Part of this scene, Chris spending time with the L.A party girls, is still in the theatrical trailer.