A lot of the actors playing zombies were carrying remotes in their hand to discharge a blood cannon placed on their back. This would activate an explosion of blood behind them, to simulate the effect of a gunshot to the head.
For the scene where Ana stitches Kenneth's wounds, the director hired a real nurse for the close-ups. She misunderstood the director's directions to go deeper and inadvertently punctured Ving Rhames' skin and stitched the prosthesis to his arm. He didn't say anything until after the scene was done filming and the director thought the blood was merely "a really good effect".
Different colors of blood were used for zombies in different stages of decomposition: red for the recently dead, a browner version for the ones that have been dead for a few weeks; and a blacker, oilier version for the ones that have been dead for a considerable period of time.
The two zombies with missing limbs (the jogger missing an arm and the legless zombie in the parking garage) were both played by actual amputees. The same thing was done for one of the first zombies seen in the original Dawn of the Dead (1978).
Director Zack Snyder personally chose most of the music used in the film. His choices included "The Man Comes Around" by Johnny Cash, and Richard Cheese's cover of Disturbed's "Down With the Sickness". Snyder was the only person who thought these songs should be in the film, as most of the producers were against it.
In an aerial scene in the first 10 minutes when Ana is driving down a highway, a truck can be seen crashing into a gas station/diner. This is a reference to Night of the Living Dead (1968), as Ben mentions he was listening to a radio in a truck in a diner parking lot when a truck crashed into the gas pumps.
Actors Ken Foree, Scott H. Reiniger and Tom Savini all appeared in the original 1978 version of this film, but playing different characters. Ken Foree delivers the tagline he delivered as "Peter" from the 1978 version of Dawn of the Dead; "When there's no more room in Hell, the dead will walk the Earth."
This is the first movie to broadcast the first ten minutes uncut on network TV, five days before its nationwide release. The showing was broadcast on the USA network, and on Channel 4 in the UK with a special introduction by film critic (and major horror fan) Mark Kermode.
According to the director's commentary, when you see the shot of the truck exploding after crashing into the gas station, the helicopter in the sky is a shot from the original that was added in post-production.
The DVD box text implies that the cause of the zombie plague is a virus. But in an interview on FeoAmante.com screenwriter James Gunn denies the virus theory, stating that a zombie bite is like a vampire bite. Thus the plague is supernatural, not scientific. However some vampire movies suggest that vampirism is a disease caused by a virus. For example, the Blade Trilogy.
The group in the mall had named the two parking shuttles; the first one, holding Nicole, CJ, Michael, and Ana was named The Pinta, the one carrying Terry, Kenneth, Steve, Glen and Monica was named The Santa Maria.
The scene between Sarah Polley (Ana), Mekhi Phifer (Andre), Jayne Eastwood (Norma), and Kim Poirier (Monica) at the Hallowed Grounds Café was re-written in order to include actress Kim Poirier to give her more screen time since director Zack Snyder and producer Eric Newman enjoyed her performance so much. However, her character's name is never once mentioned throughout the entire film. Also most unfortunate, a lot of her dialog scenes were trimmed or eliminated from the film, such as the dinner scene.
In the opening scene, where Ana is driving with an overhead view, and the two cars collide to hit the gas pump, a helicopter is seen flying through the air. This is a replica of the helicopter used in the original Dawn of the Dead (1978).
The movie trailer shows Andre checking the mall entrance when several zombies attack the outer doors. This scene was replaced in the film with a subdued version showing only one frail-looking zombie pouncing on the glass door. However, the clip used in the theatrical trailer is available for viewing on the DVD and has director commentary explaining why he changed the scene.
An extra on the DVD release for this film, "We interrupt this program", a fake newscast depicting the start and spread of the zombie infection, contains some characters whose dialog consists of lines from the original Dawn of the Dead (1978) and Night of the Living Dead (1968).
The mall scenes of the film as well as the rooftop scenes were shot in the Thornhill Square Shopping Centre in Thornhill, Ontario and the rest of the scenes were shot in the Aileen-Willowbrook Neighborhood of Thornhill, and the Township of Caledon East, Ontario. The set for Ana and Louis's bedroom was constructed in a back room of the mall. The mall was defunct, which is the reason the production used it; the movie crew completely renovated the structure, and stocked it with fictitious stores after Starbucks Coffee and numerous other corporations refused to let their names be used (two exceptions to this are Roots and Panasonic). Most of the mall was demolished shortly after the film was shot. The highway in the overhead composite shot of Ana driving past the exploding gas station is HWY 50, one kilometer south of Bolton, Ontario. The Crossroads Mall is a small strip-mall at the intersection of HWY 9 and HWY 27 just north of Caledon East. The second converted mall shuttle (with the fire damage) was shipped out of Bolton in the summer of 2006.
The first scene in the basement finishes when Michael burns the zombies with fuel from the gas station and CJ's lighter. This is a reference to a similar scene in George A. Romero's Night of the Living Dead (1968).
Visible in Luda's room is a can of something called "Smeat" - a takeoff on Spam. Smeat had previously appeared in Waterworld (1995). The Smeat can here is circular, however - in Waterworld, the cans were rectangular, like Spam cans.
Tom Savini, who played the leader of the motorcycle gang in the original Dawn of the Dead (1978) has a cameo here as the County Sheriff being interview shortly after the security guards give Sarah and her group refuge upstairs in the mall.
An exchange between Kim Poirier (Monica) and Lindy Booth (Nicole) about Nicole playing with the dog more than she is helping was eliminated from the film in order to avoid making Kim Poirier's character sound "too bitchy."
Former MTV/MTV2 VJ Iann Robinson has an uncredited cameo as a zombie. When first entering the mall, the group is charged by an Asian man-turned-zombie. The large zombie behind the Asian man is played by Robinson.
Towards the end of the movie, when the survivors get into an elevator to escape the zombies, they all go quiet and Muzak can be heard. C.J. smiles and says, "I like this song." The song is a version of Air Supply's "All Out Of Love."
A UK MTV Host, Alex Zane, is featured during the zombies' rampage through the mall. After interviewing Zack Snyder he was invited to be in the film, thus as we see the zombies running past the camera once they've entered the mall, he is clad in a bright white checkered shirt.
In a scene where the cast is in an elevator you can hear Air Supply's All Out of Love. James Gunn, who wrote the screenplay for Dawn of the Dead also directed Slither in 2006, and used Air Supply's Every Woman in the World as a major theme throughout the film.
Zack Snyder: a member of a commando unit (with shades holding an assault weapon) in front of the Capitol Building in Washington, DC. This scene can be seen during the opening credits montage of video/news clips of zombie attacks.
The trivia items below may give away important plot points.
For the graphic scene in which Monica is accidentally chainsawed to death, a full body cast was made of actress Kim Poirier which included a reloadable cartridge down the area that was to be chainsawed. This was then packed solid with bloodbags. This meant that the cartridge could be taken out and reloaded for each take.
According to "the lost tape", which contains gun shop owner Andy's personal video diary (accessible as a bonus feature on the director's cut DVD), the main characters arrive at the mall early in the movie on May the 9th. Therefore, the movie opens a day earlier on May the 8th (Andy mentions that attacks on citizens by the undead had already started on the 7th). Andy makes his last entry just before he turns into one of the undead on June the 6th, and the movie ends on that same day (not including the footage during the end credits). This places the events of Dawn of the Dead in a space of just 29 days - and all the action between the credits begins and ends at dawn.
When Andy meets his demise, it seems that his head explosion was a CGI constructed effect, however it was done using a prosthetic head, modeled on the actor, this can be seen on the director's cut DVD extras.