Lon Chaney Jr. was known for his hard-drinking ways. During production of this film, Chaney became inebriated while in full costume and got "lost" in the intricate mazes that were part of the laboratory sets. It took several minutes for him to find his way free. A similar incident occurred many years later when Chaney played the Frankenstein Monster on an episode of Tales of Tomorrow. Once again, Chaney became intoxicated and mistakenly believed that the show's live telecast was actually the final dress rehearsal. For much of the performance, Chaney stumbled about, picking up breakaway props he was supposed to destroy and then setting them back down.
It was reported that the rubber headpiece used for the Frankenstein monster make-up was very uncomfortable for Lon Chaney Jr. to wear. It sat directly on his forehead and he constantly complained. Once he asked for it to be removed. Angry and frustrated when no one listened, he ripped it off himself, tearing open a bloody gash in his forehead. Production on the film was shut down for a couple of days.
Ygor and the Monster weren't the only characters who came back from the dead. Michael Mark and Lionel Belmore, who play the two council members murdered in Son of Frankenstein (1939) are back as council members in this one, seemingly none the worse for wear.
Dwight Frye appears as 2 different characters. First as one of the villagers who destroys the Frankenstein castle at the beginning of the film. Later in flashbacks to the original Frankenstein (1931) where he played Fritz, the hunchbacked assistant to the original Dr. Frankenstein.
The first draft of the script was written by Eric Taylor was considered too depressing. The original Taylor treatment brought Wolf von Frankenstein back into play, as well as Ygor, plus a misshapen hunchback, Theodor. Ygor's plan was to create a vengeful mob of society's rejects, ala Freaks (1932), led by himself, with the Monster as brute force. A rewrite was ordered and given to veteran writer Scott Darling who retained the fundamental scenario but made significant changes.
In addition to the woes Lon Chaney Jr. experienced from wearing Jack P. Pierce's makeup and prosthetic devices, the makeup he had to wear in order to portray the Monster emerging from the dried sulfur was a particularly difficult burden for Chaney. In order to get the right look for the Monster trapped in the dried sulfur from the sulfur pit, Pierce essentially covered Chaney with cement and only provided a hole for him to breath out of by placing a straw in his mouth. The makeup process lasted from around 6:00 am until noon, at which point the cast and crew all went to lunch, leaving Chaney alone on set while his cement-based makeup dried.
Boris Karloff, then acting in the hit Broadway show which became Arsenic and Old Lace (1944), had no interest in working on the film. Producer George Waggner wisely decided to retain Karloff's make-up out of fear that the public would not accept any change in the monster's appearance.
Four of the principal actors from Universal Pictures' The Wolf Man (1941), which had finished shooting just a few weeks before production began on this film and which was released during production, also appeared in this movie. Lon Chaney Jr., Ralph Bellamy, Bela Lugosi, and Evelyn Ankers all also appeared in this film; with the exception of Lugosi, each portrays a character very similar to their roles in The Wolf Man.
This film featured the smallest budget for a Universal Pictures' Frankenstein franchise film up to that point. Budgets would continue to be slashed in the future films, and this would prove to be the final Frankenstein film shot by Universal's A-unit production crews.
Lon Chaney Jr. developed a serious allergic reaction to the makeup required to play the Monster. At one point, he developed such a bad rash that production had to be halted for several days in order for him to recover.
Reaching a height of 6'3" and weighing in at 220 pounds, Lon Chaney Jr. was a large man even before he was "enlarged" for the role of Frankenstein's Monster. After Chaney had donned Jack P. Pierce's makeup and prosthetic devices, he stood 6'9" tall and weighed 284 pounds.
Although this film refers back to its predecessor, Son of Frankenstein (1939), and derives much of its plot from events that happened in the previous film, it rather notoriously revives several characters who had died in the previous film. The Monster, Ygor, and the councilmen played by Michael Mark and Lionel Belmore all return after meeting their ends in Son of Frankenstein. Universal Studios refused to acknowledge this perplexing revival as an error, and instead publicly announced that the return of these characters (even the rather minor councilmen characters) provided a continuity to the rest of the franchise that the public craved.
This is the final Frankenstein film to feature the Monster by himself. Each remaining Universal Pictures' Frankenstein sequel featured a pairing of Dr. Frankenstein's creation with one or more of the title monsters from the rest of Universal's horror canon.
The trivia items below may give away important plot points.
Lionel Atwill's character (Dr. Bohmer) is responsible for ensuring Ygor's (Bela Lugosi) brain is switched with that of the monster (Lon Chaney Jr.) making him far more dangerous than he was before. In Man Made Monster (1941) Atwill plays a mad doctor who makes Chaney Jr.'s character dangerous via electricity (which originally brought life to the Frankenstein Monster)
This is the only film in Universal Pictures' Frankenstein franchise in which a member of the Frankenstein family, in this case Dr. Ludwig Frankenstein, is killed. Several characters in several of the sequels mention that the original Dr. Frankenstein (whose name changes from film to film) is deceased, but his death occurs off screen and does not take place in any of the films.