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.
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, the founder of Facebook, in the film The Social Network (2010).
In season 9: episode 23, "Rat Girl," of Cheers (1982-1993), when comparing Hostess snacks, Woody Harrelson says, "Gentlemen, I have one word for you: Snowballs! Snowballs are better because they are bite sized." He then proceeds to shove a whole one in his mouth. In Zombieland (2009), Harrelson's character hates Snowballs.
The deleted scenes section of the DVD reveal that the closeups of the scene, with the girls riding the drop tower, were filmed against a green screen. These deleted scenes also indicate the master was shot in 16:9 format and then possibly cropped (to around 21:9), as boom mikes are clearly visible.
When Wichita, Little Rock, Columbus and Tallahassee stop in Hollywood to pick up a map, a marquee showing the 2009 film "2012," which also starred Woody Harrelson (Tallahassee), can be seen in the upper right corner.
Whilst Tallahassee rages about the lack of Twinkies during the "Snowball" scene, he should have looked further behind the door of the truck. Hidden from his point of view, but just visible on the right hand side of frame, the truck does actually contain some Twinkies.
Towards the beginning, when Columbus is first seen walking on the deserted highway, he passes a minivan to his left that has a 99X sticker on its back window. 99X was an alternative radio station in Atlanta, GA that was hugely popular during the mid to late '90s.
When Tallahassee and Columbus steal the yellow Hummer, the Van Halen song "Every Body Wants Some" can be heard. This song is also played in the Pig Burger during Lane Myer's fantasy sequence in Better Off Dead... (1985).
Early in the movie when Columbus and Tallahassee first meet on the highway and are in their armed stare down the pocket watch tune from Sergio Leone's "For a Few Dollars More" can be heard playing faintly.
The trivia items below may give away important plot points.
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.
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."
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.
In Zombieland, Woody Harrelson is always on the look out for Twinkies and is extremely upset when he finds a truck full of Snowballs instead. In the show Cheers, specifically the episode titled 'Rat Girl,' Woody Harrelson's character states that he thinks Snowballs are better than Twinkies because they are 'bite-sized' and shoves a whole Snowball in his mouth.