- Ability over Appearance: According to details written in the early script of the show's pilot episode, Fiona Gallagher was originally supposed to be very average-looking and overweight, with rattier clothes and messy blonde hair; a huge contrast from the slender, brunette beauty Emmy Rossum.
- Acting for Two: William H. Macy played both Frank and Jerry Gallagher, identical twins. Its greatly subverted when the character is never seen again after the first season, but is referred and talked about.
- Approval of God: Paul Abbott was originally against the idea of an American remake, fearing it would be stereotypically set in the South. He changed his mind, once John Wells told him it would take place in Chicago.
- Directed By Castmember: William H. Macy directed an episode for season five.
- Fake Nationality: The actor who plays Estefania's father is actually Portuguese, not Brazilian. He speaks very few lines in Portuguese for it to be noticeable, though.
- The Other Darrin: Jane Levy played Mandy in season one, before departing the show for Suburgatory. Emma Greenwell replaced her starting with the second season.
- The Other Marty: Allison Janney played Sheila Jackson in the original pilot, but when the producers decided to expand the role, Janney had to drop out, because she was a full-time regular on Mr. Sunshine, so Joan Cusack was cast.
- Playing Against Type: Both William H. Macy and Emmy Rossum play characters almost diametrically opposite from what they were known for before.
- What Could Have Been: Woody Harrelson was originally set to star as Frank Gallagher, back when the show was to air on NBC, then HBO, and then Showtime, before dropping out after the success of Zombieland.
- Written By Castmember: William H. Macy wrote an episode for season two.
Trivia / Shameless (US)