In Curt Siodmak's original script for the film, whether or not Lawrence Talbot really underwent a physical transformation to a werewolf or if the transformation simply occurred in his mind was left ambiguous. The Wolf Man was never to appear onscreen. Ultimately, the studio determined that Talbot's literal transformation into a werewolf would be more appealing to the audience and thus more profitable. The script was revised accordingly.
Many of the modern myths of werewolves originated from this film, such as a person becoming a werewolf through a bite, the only way to kill a werewolf is with a silver bullet, and werewolves and their victims being marked with pentagrams. Some are taken from the earlier, unsuccessful werewolf movie Werewolf of London (1935) (which also made them up out of whole cloth), and others are original concepts created by writer Curt Siodmak. In folklore, one became a werewolf by being cursed or by making a pact with the devil, you could turn at any time, and werewolves were mortal and could be killed by conventional means. Later films added the detail of werewolves being immortal; again, an invention of Hollywood, and basically an excuse to keep bringing the character back for sequel after sequel.
According to the documentary on the Recent Wolf Man DVD collection, the script for The Wolf Man was influenced by writer Curt Siodmak's experiences in Nazi Germany. Siodmak had been living a normal life in Germany only to have it thrown into chaos and himself on the run when the Nazis took control, just as Larry Talbot finds his normal life thrown into chaos and himself on the run once he is turned into a werewolf. Also, the wolfman himself can be seen as a metaphor for the Nazis: an otherwise good man who is transformed into a vicious killing animal who knows who his next victim will be when he sees the symbol of a pentagram (i.e., a star) on them.
"Even a man who is pure at heart, and says his prayers by night, may become a wolf when the wolfbane blooms and the autumn moon is bright." This quote has been listed in some sources as an authentic Gypsy or Eastern European folk saying. Writer Curt Siodmak admits that he simply made it up. Nonetheless, the rhyme would be recited in every future Universal film appearance of the Wolf Man, and would also be quoted in Van Helsing (2004). (Albeit, slightly modified, "The moon is shining bright." rather than "The autumn moon is bright.")
Larry Talbot and his father Sir John attend church on Sunday in the village, but the doorway and steps of the village church looks more like that of a cathedral. In fact, it was a cathedral - part of the original set built for the legendary silent version of The Hunchback of Notre Dame (1923), which had starred Lon Chaney Jr.'s famous father, Lon Chaney and which stood on the Universal back lot for over 20 years.
Larry's silver wolf-headed cane, the only known surviving prop from the movie, currently resides in the personal collection of genre film archivist Bob Burns. Burns, who was a schoolboy at the time, was given the cane head by the man who made it for the film, prop-maker Ellis Burman.
In this movie, we're told that a werewolf is "a human being who becomes a wolf at certain times of the year ... 'when the wolf-bane blooms and the autumn moon is bright,'" and the moon is never depicted in the film. This is the only one of the Universal series of Wolf Man films in which the full moon is never shown. In the sequel, the folklore is changed to "when the moon is full and bright."
In the first version of the script, Larry was not the prodigal son of Sir John Talbot, nor related to him in any way. He was an American engineer who comes to fix Sir John's telescope, and ends up getting trapped in the werewolf curse.
Curt Siodmak claimed that he is responsible for the addition to canon of the werewolf's vulnerability to silver, and this claim has often been repeated by horror aficionados, including director John Landis. However, silver, according to legend, was first used to slay a werewolf in the Beast of Gevaudan, dating from the late 19th century. Novels recounting the legend appeared in the 1930's, and featured the slaying of the werewolf with a silver bullet. The Wolf Man, however, was the first film to utilize the silver bullet myth onscreen.
This film marks the first of five appearances by Lon Chaney Jr. as the Wolf Man for Universal Studios. Out of Universal's classic canon of monsters, Chaney was the only actor to portray the same character in each of the studio's classic films and sequels.
Jack P. Pierce achieved the Wolf Man's iconic makeup primarily with a rubber nose and yak hair which was singed with a curling iron and attached to Lon Chaney Jr.'s face, arm, and legs with spirit gum.
Evelyn Ankers had a rough time on the set. Lon Chaney Jr. delighted in sneaking up on her in full makeup and scaring her senseless. In other deleted scene, a bear was to wrestle with the werewolf but broke loose, chasing the actress up into the soundstage's rafters.
Universal, lacking a theater chain, had planned to market the film as part of a double bill (with The Mad Doctor of Market Street (1942)) but feared that the public would avoid an all-horror bill after the attack on Pearl Harbor.
For one scene, Evelyn Ankers had to faint and fall to the misty ground but the fog fumes were so strong she passed out. Unnoticed by the director and crew who were concentrating on another aspect of the scene, she remained there unnoticed until a studio technician began breaking down the set.
The first transformation takes place with Talbot in an undershirt (although he is fully dressed in a dark shirt once on the prowl). Only the feet transform on screen in six lapse dissolves. In the second transformation there are eleven shots - again of feet only. The third transformation features 17 face shots in a continuous dissolve.
Evelyn Ankers suffered a bad scare when a 600-pound bear (his sequence in the film was later cut) escaped its trainer and chased the actress up a ladder where she was pulled to safety by an electrician.
Evelyn Ankers had difficulty working with Lon Chaney Jr.. Already peeved at Ankers because she was given his dressing room (the studio was punishing him for vandalizing studio property while drunk), the actor would constantly irritate her, nicknaming her "Shankers" while playing juvenile, practical jokes; he liked to sneak up on her in full makeup and scare her.
In this film, Claude Rains portrays the father of Lon Chaney, Jr., who was the son of Lon Chaney, Sr. Thus, Lon Junior's on-screen father and real-life father have both portrayed The Phantom of the Opera in feature films - Lon Senior in the 1925 original and Claude in the 1943 remake.
The trivia items below may give away important plot points.
Evelyn Ankers later recalled that during the filming of the final confrontation, she was required to faint, and then to stay on the floor until the fight scene between Lon Chaney Jr. and Claude Rains was finished. Ankers recalled that during one take, she stayed on the floor so long that the low-hanging chemical fog being used in the scene caused her to pass out. When the take was over, the film crew began rearranging the cameras and lights for the next take, not noticing that Ankers had not emerged from the floor. Finally someone on the crew realized that Ankers was missing, and she was pulled up from the fog and revived.
Silent film actor Gibson Gowland appears in this film as a villager present at the death of Larry Talbot. He also had been present during the Phantom's death scene in the 1925 version of The Phantom of the Opera (1925), becoming the only actor to appear in death scenes performed by both Lon Chaney and Lon Chaney Jr.