The theatrical trailer utilizes the song "In Da Club" by 50 Cent as Tree's birthday ringtone. However, the final film does not feature this as the crew and studio could not acquire the rights. As a result, an original ringtone composition was concocted.
The Bayford University Baby killer costume was designed by Tony Gardner, who also designed the Ghostface mask, the horror icon of the Scream franchise and which is a reworked version of the Father's Death Halloween costume.
An original ending featured Tree Gelbman murdered again, thus entering another time loop. The test audience reacted furiously to this ending, feeling betrayed that the protagonist, after becoming a better person, could not break free. This ending was conceived as a way of leading the viewer to believe it was never going to end.
Carter points out the similarities between Tree's situation and the film Groundhog Day (1993). There are in fact a few scenes that directly parallel that film's events. Just like Phil, Tree proves that she has lived through this day by correctly pointing out several events about to take place around her. One of them is a frat brother passing out, whom she helps with a pillow. This may parallel the dying old man that Phil finds and tries to rescue. Phil points out that a waiter in the diner is gay, and Tree eventually finds out that Tim is gay. Her repeated unwanted encounters with Tim are similar to Phil running into Ned Ryerson. Two of Tree's deaths involve getting hit by a bus and hanging herself in a bell-tower. Two of Phil's suicides involved walking in front of a bus and throwing himself from a bell tower. Lori's last name is also Spengler, which was the name of Groundhog Day (1993) director Harold Ramis's character in Ghostbusters (1984), which also paired him with Bill Murray.
During the climactic fight, Tree punches Lori in the throat and forces the cupcake into her mouth. A blow like that to the throat would cause the esophagus and windpipe to swell shut, rendering Lori unable to breathe or swallow the cupcake.