When the cast is looking at the poster for 'Gay', the names of Graham Linehan, Jamie Glazebrook, and other members of the production crew are listed in the credits for the musical.
Producer Ash Atalla (a wheelchair user) appears as 'rampant gay man' in this episode involving wheelchairs.
Moss hears Jen and Roy debating whether Phillip is gay and, jumping to a false conclusion, says 'Everyone knows. And what's more he's been gay since Wham'. Moss is referring to George Michael, whose sexual orientation was a subject of speculation until 1998 when he was arrested in an L.A. public restroom for lewd behavior.
The facade of the New Wimbledon Theatre was used for the outside shot of the "Gay!" musical venue. It is the same theatre used in Something Happened (2010).