The opening flashback confirms a horoscope Shawn wrote in Meat is Murder, but Murder is Also Murder (Henry Spencer: [reading his horoscope] Sagittarius: Please return the BB gun you confiscated from your son in the second grade. P.S. You are a cranky-pants.)
While Juliet is skating in the roller derby, the song "Check Yes Juliet" by We the Kings is playing in the background. The move of knocking other players over is called "checking."
Maggie Lawson is not actually skating in the close-up roller derby shots, she is simply swaying back and forth while standing on the camera truck. Only in the wide shots is she really skating.
Shawn mentions the ongoing 3-hole punch reference while on the phone with Juliet right before they follow Westwood. The reference featured in the show's outtakes involves the cast and crew laughing hysterically at the mention of the phrase "three-hole punch." According to James Roday, the gag began with a script written by Tim Meltreger, which included a joke about a three-hole punch. During filming, Roday misspoke the line as "three-hole puncher." Meltreger called for a cut and raced onto the set, then insisted that Roday read the line exactly as scripted, because, in his words, "Three-hole punch is *way* funnier than three-hole puncher!" Subsequently, it became a running joke on the set: someone says the words "three-hole punch" while shooting and the cast and crew all pretend to laugh as if it's the funniest thing they've ever heard.
The characters of Westwood, Wilde, and Fox are named after three radio DJs from the Los Angeles area: Denise Westwood, Rita Wilde, and Cynthia Fox. At the time, all three women had radio shows on KLOS (95.5 FM), a classic rock station that the writers listened to frequently at work.