Towards the end of the movie, Herman (Fred Gwynne) and Grandpa (Al Lewis) are shouting for help. Herman says, "Call Batman," then adds, "Car 54, where are you?" Car 54, Where Are You? (1961) was the title of a 1961 comedy series that featured both Gwynne and Lewis.
The Munsters (1964) series director Gene Reynolds was the original choice to helm this movie, but found it difficult to work with the director of photography and was fired after just a couple of days for not working fast enough (the film had to be shot in 18 to 25 days).
This theatrical film was not a great success at the box office, prompting Paramount, which had been contemplating a theatrical version of Get Smart (1965), to cancel that and instead spread it out over 3 episodes of the TV series called "A Man Called Smart", Parts 1, 2, and 3.