Although he doesn't appear onscreen, Keenan Wynn has an uncredited role in this film: he was Aunt Wendy's late husband, Henry, and a painting of him appears above her money safe when she makes withdrawals.
Toni Basil, and Teri Garr - who appear in the clothing/modeling scene - had a history of working as dancers together. They were also featured in ShInDiG! - which Ms. Basil also served as choreographer on.
First feature film to introduce the new Ford Mustang. Even though "Goldfinger" is commonly credited with this distinction, Goldfinger wasn't released until January, 1965. In Pajama Party, Annette is seen driving the Mustang in several scenes.
Frequently referred to as an entry in the "Beach Party" film series, with the relatively brief appearances of Harvey Lembeck as Eric Von Zipper and Candy Johnson as Candy supporting that, the fact that major players Annette Funicello, Jody McCrea and Don Rickles are not in their usual roles (Connie, Big Lunk and Big Bang [a Martian] here instead of Dolores/Dee Dee [a nickname], Bonehead and Jack Fanny/Big Drag/Big Drop [the man kept changing his "name" with his career] in the other movies, respectively) suggests the contrary with much more strength. However similar the characterizations are, they are at least nominally different characters.