Among the names Mira gives Shawn from her long list of ex-boyfriends are "Gay Andy" and "Guru Anupam" - a reference to series writers Andy Berman and Anupam Nigam.
Shawn's excuse to not go rock climbing with Mira is that he and Gus got a call about a ghost in a ballroom. This was the circumstances of the first ghost hunt in Ghostbusters (1984). Gus' dad, introduced in the previous episode, is played by Ernie Hudson, who was also one of the Ghostbusters.
After Shawn finds out that Gus got married to Mira, Gus tells him that when when he gets married for real that Shawn would be there. In real life when Dule Hill got married for the second time James Roday Rodriguez was there.
Spot the pineapple: while golfing Shawn is wearing a pink t-shirt with a little pineapple logo.
Shawn describes the riddle he told Gus as ending with "The doctor was a woman!". This is the punchline to the classic riddle that goes along the lines of "A father and son are in a plane crash (or car crash, or train accident) and the father dies. When the boy is taken in for an operation, the doctor/surgeon says 'I can not do the surgery because this is my son'. How is this possible?" Even today, a large portion of people arrive at answers other than the doctor being the patient's mother, including doctors of all genders and those whose own mothers are doctors and surgeons.