In "Fears" Phil speculates if there is treasure hidden under the porch and then if the Declaration of Independence is hidden in the attic, a reference to Ty Burrel's character in National Treasure 2.
Luke tells Claire it would be cool if their plane crashed like in LOST; Julie Bowen appeared as Jack's wife in a few episodes (though she never appeared on the island).
The entirety of "Fizzbo" for Eric Stonestreet, who created the clown character for himself at age 11.
Pepper says of "Walk Like a Man," "I can sing it but I can't do it," referencing Nathan Lane's character in The Birdcage.
Jay Pritchett is an Ohio State University fan, and appears to have lived in Ohio for some time at least as in "Goodnight Grace" he asks a woman if she had ever lived in Ohio after recognizing her (but unable to figure out who she is). Ed O'Neill was born and raised in Ohio.
He's also depicted as having been a college football quarterback. Again, in real life, Ed O'Neill played linebacker at Youngstown State, well enough for him to have been signed by the Pittsburgh Steelers.
One episode, while showing Mitchell self defence moves, mentioned that he "learned this from the Gracie's". Ed O'Neill is a Jiu-jitsu black belt, having trained with Rener Gracie himself
Dyeing for Your Art: Sofia Vergara is naturally blonde. Her hair has gotten lighter as the series has gone on but it's still darker than her natural hair color. She began dyeing it early in her career when she was told that people wouldn't find a blonde Latina believable.
Executive Meddling: Parodied in the show's sketch at the 2010 Emmy Awards, which shows various proposed "changes" to the show, such as: having Cameron and Mitchell adopt Stewie, making Cameron and Mitchell not gay, shooting the show in 3D (with an emphasis on shots of Sofia Vergara's chest), and replacing Ed O'Neill or Ty Burrell with George Clooney.
Though some viewers may not mind the last two ideas.
Danny Trejo, usually typecasted as brutal gangbangers or such... is a nice man that helps Claire out with setting up dance decorations.
Jay is Al Bundy (Ed O Neill), making the fandom think that this is what happened to Al after he finally got rid of Peg (or Peg chose to walk out on her own accord) and Bud and Kelly moved out on their own.
The Other Darrin: Lily was recast for season three when it became clear the little girls playing her really didn't like acting.
Reality Subtext: "Suddenly, Last Summer", the fifth-season premiere episode, was set on June 26, 2013, the day three months earlier that the U.S. Supreme Court upheld a lower-court decision that invalidated California's Proposition 8 and thus relegalized gay marriage in California—setting up a plot where Cameron and Mitchell connive with other members of their extended family to come up with a more romantic marriage proposal.
Teen Genius: Nolan Gould in real life, having graduated high school at age 13.
Troubled Production: Showrunners Steven Levitan and Christopher Lloyd had a major falling out after the first few seasons and now refuse to work together, each tackling half a season's episodes on their own.
Word Of God now is there is no documentary crew. The show is only filmed in a documentary style and the talking heads are the characters Breaking the Fourth Wall. It explains how the camera can suddenly be in a building before a character enters it.