Due to limited space for the puppeteers, in the scene where the car is full of The Muppets after picking them all up, Amy Adams and Jason Segel were asked to operate the Muppets on either side of them.
During an interview with Terry Gross on her National Public Radio program "Fresh Air," Jason Segel said that during filming, he observed the choreographer, Michael Rooney, giving instructions to the classic movie star Mickey Rooney (who had a cameo in the movie) and calling him "Dad." Segel went up to Michael and reprimanded him, saying "you can't just call any old man 'Dad,'" and Michael told Segel, "no, he's my actual Dad."
Producers gave Jason Segel (Gary) a feedback card from a child audience member at an early test screening of the film. The producers attached a handwritten note to Jason's feedback card that said, "To keep you humble." When asked to describe what the child audience member did not like about the film, the child wrote in response, "Gary's face."
Dave Grohl: as Animool, the only human character of the Muppet impersonation act in a Reno nightclub called "The Moopets."