The show was almost cancelled during the first season. But was decided to give the show a chance to grow.
Ep. 1 The Gang Gets Racist The Waitress, played by Mary Elizabeth Ellis, is Charlie Day's wife in real life.
Ep. 4 Mac Bangs Dennis' Mom When Frank is on his date with Angie, the young girl that Frank checks out is Danny DeVito's daughter Lucy Devito.
Ep. 1 The Gang Finds a Dumpster Baby Rob McElhenney (Mac) and Kaitlin Olson (Sweet Dee) are actually married in real life. In season six, Kaitlin was pregnant with their first child. Her pregnancy was written into the show.
Ep. 10 The D Caylee, the woman Dennis uses the D.E.N.N.I.S. System on, is Glenn Howerton's wife in real life.
Ep. 7 Who Got Dee Pregnant In "Who Got Dee Pregnant?", the McPoyle's inform Mac that their sister is still expecting a call after their sexual intercourse, though since their sister is both deaf and mute a phone call would serve no purpose.