The 22 Jan 1965 DV listed upcoming projects at American International Pictures (AIP), including the film under its working title, Pajama Party in a Haunted House, with Frankie Avalon and Susan Hart in lead roles. The 22 Nov 1966 NYT later explained that the picture was an attempt by the studio to combine two of its signature genres, beach party and gothic horror. Production was scheduled to begin 8 Sep 1965, according to the 7 Jul 1965 Var.
       News items in the 25 Jun 1965 DV and the 26 Jun 1965 LAT stated, respectively, that veteran actors Elsa Lanchester and Buster Keaton had joined the cast. In addition to their acting duties, Lanchester and Keaton were commissioned by AIP to coach its roster of young contract players. Hedda Hopper, in her 26 Aug 1965 LAT column, suggested that the multigenerational cast would attract a larger audience. Other castings included AIP regulars John Ashley and Jody McCrea (3 Jul 1965 LAT), and Francis X. Bushman in what was reportedly his 435th picture (17 Sep 1965 LAT). Among the featured performers were fourteen-year-old Italian singer Piccola Pupa and The Bobby Fuller Four in their only screen appearances. Principal photography was anticipated to begin 29 Sep 1965, as noted in 3 Sep 1965 DV production charts. By this time, Frankie Avalon, John Ashley, Jody McCrea, Buster Keaton, and Elsa Lanchester had left the project. Production charts in the 26 Oct 1965 DV revealed that Keaton was in Spain, appearing in A Funny Thing Happened on the Way to the Forum (1966, see entry), which began filming 30 Aug 1965. Bushman died 23 Aug 1966 of a heart attack. The picture also marked the final screen appearance of actor-restaurateur Philip Bent, who, according to the 13 Jul 1966 NYT, died after crashing his airplane off the coast of La Jolla, CA. Also killed in the wreck was psychologist Peter Sachse, whose wife, Salli Sachse, appeared in the film as well. Bobby Fuller’s death on 18 Jul 1966 was officially ruled a suicide, although rumors of foul play have persisted over the ensuing decades.
       Retitled The Ghost in the Invisible Bikini, the picture opened in Apr 1966 to lukewarm notices and reportedly indifferent public response. AIP discontinued its “Beach Party” series, focusing its efforts on what the 22 Nov 1966 NYT described as “protest films,” beginning with The Wild Angels (1966, see entry).