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Sarah, portrayed by Mindy Kaling, refers to The Office (2005), when her character is introduced in the karaoke bar. Kaling is famous for her long standing role on that show.
Director Jonathan Levine revealed on Collider that a lot of the film's comedy was improvised, and the dramatic moments were per the written script, which he admitted was more like an outline guide.
In the limousine, Isaac, played by Seth Rogen, calls Ethan "Joseph." Ethan is played by Joseph Gordon-Levitt.
Some of this movie was filmed in August. The cast said they felt really hot in the Christmas sweaters they had to wear outdoors in summer.
There are many references to Die Hard (1988), including a character who likes to imitate Hans Gruber, the music to Ludwig van Beethoven's 9th Symphony, and characters singing Run-D.M.C.'s "Christmas in Hollis."
The nude photos were provided by a body double.