Australian actress Betty Bryant was originally cast as Ann. She fell ill as filming started and a doctor was called in by the studio. Unfortunately for Bryant, the doctor developed an unhealthy obsession with her and began stalking her at the studio and making things difficult for the production. Bryant was replaced by Amelita Ward nine days into filming (source: "Universal Horrors" by Tom Weaver, Michael Brunas, and John Brunas).
Johnny, errand boy:
Ah, my dear Ann! So glad to see you again after all these minutes. Twenty of them, at least.
Ann Forrester: *Fifty* minutes, Johnny.
Johnny, errand boy: Fifty minutes! Fifty years away from you, Ann.
Ann Forrester: You're not flattering me Johnny. Now what have you been doing?
Johnny, errand boy: Waiting for the specimen ...
Even though the character is listed in the credits as "Dr. Stendahl", he was always referred to as "Mr. Stendahl" by all the other characters.