In trying to come up with a name for Santa's brother, Jessie Nelson, who came up with the idea for the film after her daughter asked her if Santa has a family, hit upon "Fred" while watching Le Parrain (1972) on television. The name "Fred" is an homage to the character Fredo Corleone, the unreliable middle child of the Corleone family played famously in Le Parrain (1972) and Le Parrain, 2ᵉ partie (1974) by John Cazale
Trevor Peacock, who was diagnosed with dementia in 2009, has no lines after the first scene where Nicholas is born. Peacock's longest line is, "Frederick, would you like to...come meet your brother?"
The wardrobe department consulted Levi Strauss and Company, and had special 501s created to accommodate Vince Vaughn's sizes exactly.
In this movie, Vince Vaughn portrays Paul Giamatti's older brother. In reality, Vaughn is three years younger than Giamatti.
Frank Stallone: As himself, and a member of the group "Siblings Anonymous". In the film, Stallone speaks about Rocky (1976) and Rambo (1982), two major blockbuster film series that star his brother, Sylvester Stallone.
Stephen Baldwin: As himself, and a member of "Siblings Anonymous". The youngest Baldwin brother, he expresses his issues with the eldest and arguably most famous of his brothers, Alec Baldwin.
Roger Clinton: As himself, and a member of "Siblings Anonymous". Clinton is the half-brother of former U.S. President Bill Clinton.