Elf 2: Buddy Saves Christmas is a cancelled sequel to Elf.
History
In September 2013, Mental Floss reported that Favreau was interested in making a sequel to Elf, entitled Elf 2: Buddy Saves Christmas.
Why it was cancelled
In December 2013, Ferrell stated that he does not want to make a sequel to Elf. Despite this, during an interview in January 2016, Favreau stated that a sequel to Elf could possibly be made. The next month, however, Ferrell reiterated that it is unlikely that the sequel will happen and stated that he was not interested in reprising his role.