The scene when Buddy eats different candies and pastries with the spaghetti noodles had to be shot twice, because Will Ferrell vomited the first time.
Several minor traffic accidents occurred when Will Ferrell walked through the Lincoln Tunnel in his costume, because people were so surprised (and distracted from their driving) to see him wearing an elf outfit.
Will Ferrell turned down $29 million to be in a sequel in late 2014. James Caan revealed that the reason was that Ferrell and Jon Favreau didn't get along.
The cotton balls Buddy eats while in the doctor's office were actually cotton candy that had not been dyed.
Wanda Sykes was originally slated to play the Gimbel's Manager but backed out at the last minute. She was replaced by Faizon Love, who insisted on still wearing the nametag made for Sykes, which is why his tag inexplicably says "Wanda."
Ray Harryhausen: According to The Ray and Diana Harryhausen Foundation, director Jon Favreau wanted to include stop-motion segments in tribute to classic animated Christmas specials such as La storia di Lumetto (1964). Stop-motion pioneer Ray Harryhausen was invited to record the voice of the Polar Bear Cub, one of the animals Buddy the Elf (Will Ferrell) says goodbye to when leaving the North Pole.