Yumi Shirakawa's singing voice (for the two songs in the film) is provided by noted Japanese jazz starlet Martha Miyake.
In the original Japanese version, the detectives make a big deal out of the fact that Chikako owns a television. At the time this was made, 1958, a television set was still beyond the budget of the typical Japanese family.
The dissolving effect was created by deflating life-sized inflatable human figures, filming them in fast-motion, and then running the film at normal speed.
On the lobby floor in some theaters where the H Man was a coming attraction, a melted victim was on display -- it consisted of a pair of shoes with shirt and pants and a toupee piled on top.