Contrary to popular belief, the supermarket scene was not filmed at an actual supermarket. A movie set was built from scratch to look like a real supermarket, and some of the merchandise is fake. For example, the stuff behind the glass refrigerator doors is just printed on paper. According to the producers, it was cheaper than buying out a supermarket and paying them for broken merchandise.
It has been said that this movie was supposed to be based on the video game Left 4 Dead 2 (2009). Valve, the creators and developers of the game, denied the studio permission to mention the game and company in the opening and end credits.
The biggest opening weekend of any film in Woody Harrelson's career; $24.7 million. Harrelson's previous best weekend debut was Indecent Proposal (1993), with $18.3 million. The record was beaten a month and a half later by 2012 (2009)'s $65.2 million opening. This record was then defeated by The Hunger Games (2012) with an opening of $152.5 the first weekend.
During the Monopoly game, Jesse Eisenberg's character Columbus remarks that one of the best things about Zombieland is "No Facebook status updates". Eisenberg would go on to portray Mark Zuckerberg, founder of Facebook, in the film The Social Network (2010).
The trivia items below may give away important plot points.
Columbus (Jesse Eisenberg) has 32 rules for surviving Zombieland, ten of which are identified in the motion picture. As the rules are punctuated, and in the order in which they appear in the movie, they are, "Rule #1. Cardio"; "Rule #2. Double tap"; "Rule #3. Beware of bathrooms"; "Rule #4. Seatbelts"; "Rule #7. Travel light"; "Rule #31. Check the back seat"; "Rule #18. Limber up"; "Rule #22. When in doubt, know your way out"; "Rule #32. Enjoy the little things"; and "Rule #17. Don't be a hero" (later corrected to "Be a hero"). An eleventh rule of surviving Zombieland is identified in a deleted scene. As punctuated in the deleted scene, the rule is "Rule #2. Ziploc bags". In voice-over, Columbus explains, "You've got enough problems. Moisture shouldn't be one of them."
Although his character is on a constant hunt for Twinkies, Woody Harrelson is a vegan, and does not eat Twinkies (which contain eggs and beef fat). According to Harrelson, the filmmakers made special "faux Twinkies" out of cornmeal for the scene at the end.
Six other additional rules are mentioned in the Theatrical Promo Trailers in the DVD extras. Rule # 12: Bounty (as in Bounty paper towels "If there is one way to describe Zombieland it is moist"); Rule # 15: Bowling ball ("Nothing says massive head trauma like a bowling ball"); Rule # 29: The Buddy System ("It is so important that we take a cue from our zombie neighbors and we have each other's backs"); Rule # 6: Cast Iron Skillet ("Zombie takes one of these to the head, he ain't getting up"); Rule # 33: Swiss Army Knife ("The Swiss army use that knife for a reason"). Which brings the total rules number up to 33.