The Castle-gimmick was that some of the theater seats were wired to give the occupant a shock at appropriate times during the film. Presumably the appropriate time was when the tingler escaped into the theater (the one in the movie), they cut the house lights, and Price tells everyone to scream or else the tingler will get them. That might have worked.
Velvet Worm. Wikipedia doesn't say if this species moves through the use of visible wires. Another interesting part is when the Price character wanted to feel fear (you see, he's super macho-brave and is never afraid), so he takes a hit of acid. The first time an acid trip was featured in a movie.
Typical William Castle. In a TCM Biography his daughter said of the film, the biggest obstacle for the actors was to not burst out laughing at the silly prop and absurd dialog. Typical Vincent Price rising above the source material. There was a background story about Price's philandering wife, or her sister dating his assistant (see above comment regarding a "young couple"), but it doesn't play much into the film except maybe to give Price an opportunity for biting dialog. A fair effort all-in-all. A well made, cheesy, B horror movie. AMRU 3.5.
"The tingler exists in every human being, we now know. Look at that tingler, Dave. It's an ugly and dangerous thing-ugly because it's the creation of man's fear; dangerous because... because a frightened man is dangerous."