To keep up Samantha's continuous aggressiveness and hysterics, Anna Faris continually drank Red Bulls before filming.
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.
The movie was shot during winter in Regina and Moose Jaw, Saskatchewan when temperatures would go down as low as -34°C (-29°F).
In a deleted scene, Alanis Morissette plays herself, having an antagonistic relationship with Ryan Reynolds' character. The two were dating at the time.
In the beginning when Chris is leaving the party on his bike, he paraphrases a line from Bruce Springsteen's "Thunder Road": "It's a town full of losers, and I'm pulling out of here to win."
Jake Weiner: the co-producer plays the guy who says "Merry Christmas, neighbor!" and is hit by Chris with a snowball.