When the Monster's dialogue was deleted (see Alternate Versions), also removed were any references to the Monster being blind, a side effect of Ygor's brain being implanted into the Monster at the end of The Ghost of Frankenstein (1942). As a result, Bela Lugosi's sleepwalker-like lumbering gait with arms outstretched is not explained and became the subject of ridicule. It also established the Frankenstein Monster-walk stereotype.
Several photos exist showing the deleted scenes (the fireside chat between the Monster and Talbot beneath the icy catacombs of the castle for instance; where Talbot & the audience learn that the Monster is still blind). This has been confirmed by several sources, including screen writer Curt Siodmak. In the mid-'80s a search was made through the Universal Studio vaults for a print or negative of the uncut prerelease version. As of this date, it has not yet been found.
With Bela Lugosi's dialogue scenes cut, he's only on screen for five minutes and 6 seconds, with stunt men and doubles appearing in almost two additional minutes.
When Larry Talbot discovers a photo of Elsa Frankenstein, you can see the Monster's mouth moving, but without sound coming out. Most scenes that included the Monster's dialogue were cut completely from the film or dramatically shortened. Here, Bela Lugosi's voice track was simply erased.
Originally, Lon Chaney Jr. was to play both the Wolf Man and the Frankenstein Monster, but the producers decided the make-up demands and schedule wouldn't permit this. Late in life Chaney stated in an interview that he did, however, play both monsters in the film. He may well have been referring, correctly, to Abbott and Costello Meet Frankenstein (1948) where he briefly doubled Glenn Strange after Strange broke an ankle throwing a woman through the laboratory skylight near the end of the film. You can actually see Strange stumble but keep upright after the throw.