This is apparently a lost movie, never released.
In this version, Boris Karloff, offered a generous fee, evidently again volunteered to essay the role of the immortal Monster, whilst Lon Chaney, Jr., filled in the role of the Mummy that he took on after Karloff's and Tom Tyler's brief stints in the role. According to deeply placed sources, the studio was trying to "humanize" the Frankenstein Monster, in order to engender an appeal to a "wider audience"--i.e., the "family" audience. Director James Whale and Screenwriter Curt Siodmak were ordered to come up with a more sympathetic role for the Mummy as well.
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Alas, the completed film was considered a bit over-the-top, even by studio execs. The spectacle of Karloff's Monster lumbering after Chaney's Mummy because the Monster's damaged aural organs confused "mummy" with "mommy" was reportedly enough to cause Karloff to forever remove the green greasepaint and electrodes. Whale and Siodmak demanded their names be removed from the picture. This disaster also purportedly increased Chaney's use of alcohol. Supporting actors George Zucco, John Carradine, and Evelyn Ankers constantly ruined scenes with helpless laughter, and Bela Lugosi, reprising his role of Ygor (now spelled "Igor"), reportedly said, "Monogram was never this bad!"
I want to see this movie. It cannot possibly be as bad as Troll 2.
edit for
http://www.horror-wood.com/incredible.htm