Anne Ramsey's speech impediment was caused by operations she underwent in order to treat throat cancer. She received a best-supporting actress nomination for her role in the film in 1987.
'Danny Devito' once noted in an interview with Playboy Magazine that the scene where Owen shows his coin collection to Larry, was inspired by his childhood habit of sharing things with friends that involved whatever he was into at the time. It was his insistence as a director to include a sequence like this in the movie. Writer Stu Silver then wrote the scene.
Larry on the train talks to Owen about the perfect beginning of a novel and mentions Charles Dickens' 'A Tale of Two Cities'. "It was the best of times it was the worst of times..". Momma then says, 'The night was sultry'. This is a variation of the line,'The night was so very sultry.'. A quote from the same novel.
Owen (Danny DeVito) introduces Larry (Billy Crystal) to his mother as "Cousin Paulie." In The War of the Roses (also starring and directed by Danny Devito), Gavin (Devito) tells Oliver Rose that he used a certain bit of legal precedent for a case he was doing for his "Cousin Paulie... total loser."