In a 2010 interview with "Out" Magazine, Jesse Tyler Ferguson said that the running joke that Jay kept "forgetting" that his son, Mitchell, is gay (and Mitchell had to come out to his father repeatedly) is drawn from Ferguson's real life - he had to come out to his real father three different times over many years before his father actually believed it. When Ferguson told the show's writers this story, they found it very funny and decided to add it to Mitchell's backstory.
Phil's birthday is either on April 3rd or 30th (US release dates of the original iPads). This is due to a joke in which Phil says 'The iPad comes out on my actual birthday, it's like Steve Jobs and God got together to say "We love you, Phil"'
Everytime DeDe (Jay's ex wife) comes to visit, she arrives at a different family household. In Season 1, she went to the Tucker-Pritchett's. In Season 2, she arrived at the Dunphy's. Then finally in Season 4, she came to the Pritchett's.
The original show description explained why the show was shot in a "mockumentary" style. It stated a Swedish movie director who formally was a foreign exchange student in Phil's home is shooting a documentary on the American family.
According to TMZ, Brigitte was on the books of Hollywood animal acting agency Good Dog Animals, who subleased the pup to ABC for the show before season two. But the agency recently decided it no longer wanted to work with the cute pooch and made no bones about it as Brigitte was dumped. They then replaced her with a new dog named Beatrice, who Modern Family decided to hire to take on the role of Stella for season four of the show.