- Cast Incest: James Corden and Sheridan Smith (who play brother and sister Smithy and Rudi) used to date in real life.
- The Character Died with Him: Margaret John died in 2011, and in the 2019 special her character Doris is mentioned to have died.
- Throw It In!:
- When Bryn sings "(Something Inside) So Strong" at the christening, drummer Doris' bad timing is real, courtesy of actress Margaret John's inability to find the beat. They were going to fix it in the edit until they realised it was funnier as it was.
- The first time Barry Island Promenade was shown, a dog ran straight across the shot. The writers and director liked it so much that they had the same thing happen every time the promenade was shown, turning it into a literal Running Gag.
- What Could Have Been: A US remake was made by Fox titled Us & Them to air during the 2013-2014 season. It starred Jason Ritter and Alexis Bledel as Gavin and Stacey and they would live in different states. But midway through production, Fox cancelled the series because they didn't like the scripts and shelved the seven episodes filmed, only airing them in Korea and South Africa.
Trivia / Gavin & Stacey