When Shaun is on the phone to his mum, Ed shouts "We're coming to get you Barbra". This is a tribute to the famous "they're coming to get you Barbra" line from Night of the Living Dead (1968) .
Throughout the film, several of the original music scores from Dawn of the Dead (1978) are played, such as during the Universal logo and during Shaun's several plans for picking up Liz and his mother.
Just as Shaun switches the TV off near the end of the film you can hear a reporter saying something like '...meanwhile, reports that the outbreak was caused by rage-infected monkeys have been described as bullsh*t-'. This is a jibe at Danny Boyle's film 28 Days Later - the creators of SOTD didn't appreciate the fact that in 28DL the "zombies" could run and move quickly.
Although it seems like Diane was killed after she left the Winchester, she actually does survive. If you watch the "Plot Holes" section on the DVD, Diane explains how she used David's leg as a weapon, fought through the zombies to a tree, ate part of the leg for sustenance, and then came down after everything was back to normal.
George A. Romero liked this movie so much he offered the director and the two main actors cameos in his zombie movie Land of the Dead (2005). Though Nick Frost did not accept, Simon Pegg and Edgar Wright have cameos as 'Photo Booth Zombies'.
When Shaun is searching an Italian restaurant in the Yellow Pages, he finds one called Fulci's, a reference to Italian horror director Lucio Fulci.
Simon Pegg was offered a part in Dog Soldiers (2002), but SOTD director Edgar Wright wanted this to be his first horror film, so he turned it down.
In the scene where the survivors try to get into the Winchester, and Shaun tries to lure the zombies away from Di, David, Ed, and Liz, Shaun says, "Oh boy," when he gets up on the platform so all the zombies will see him. When Shaun says, "Oh boy," like he's frightened, his fear is real and at one point in the movie Simon Pegg actually tells all the zombie actors to "f*ck off" and to end the shot for the moment because the zombie actors looked too real. Check for it, it's in the outtakes.
The pizza place next to Shaun's local newsagents is called Bub's Pizza; a nod to Day of the Dead (1985) in which the scientist's experimental zombie is called Bub.
The running gag about dogs not being able to look up was inspired by a theory that Nick Frost came up as a result of an incident that occurs in the second series of 'Spaced', a show starring Shaun Of The Dead's Frost and Simon Pegg, both directed by Edgar Wright. In a scene from Series 2, Episode 6, Daisy bangs on the window in Marsha's room and shouts for Colin, he looks round. However, he looks directly behind him rather than up where Daisy is, at the second floor window. Whether or not the theory has some truth in it, the reason behind the scene was this. The shot of Colin is from Daisy's viewpoint from the second floor window, whereas when we see Daisy it is shot from outside on the ground looking up. The sound made to get the dog to look round was made off camera at ground level. This is explained on the Shaun Of The Dead DVD cast commentary.
In the film, Matt Lucas is wearing an "I Love Pussy" T-shirt. This shirt was designed for Ed's character, but this was considered too distracting for the entire film, so Ed wears an "I Got Wood" T-shirt. Other rejected designs include "Bumpin' Donuts", "Pull My Finger" and "I'm Here About The Blowjob".