Robert De Niro wanted "Mr. Jinx" to appear in more scenes than he was supposed to because De Niro liked the cat so much. Apparently, De Niro would also play with the cat between filming scenes.
Robert De Niro originally wanted to train the cat himself, but then realized that would take up several months of his life. Instead, he would carry kibble in all of his pockets, which helped him enjoy a very cooperative relationship with the animal.
The MPAA would not allow the name "Focker" unless the filmmakers could find an actual person with that surname.
At one time, Jim Carrey was slated to star as the lead and even contributed jokes to the screenplay, such as the main character being named "Focker".
Ever the method actor, Robert De Niro chose to keep his distance from Ben Stiller during the shoot to help him maintain an aloofness between the two men.