The original script revealed Claudin to be Christine's father, who abandoned her and her mother in order to pursue a musical career. When this was excised from the final film, it left Claudin's obsession with Christine unexplained.
On 21 May 1943, the finished film was rejected by the Hays Office because of a "number of unacceptable breast shots of Christine" in her dressing room. It has not been determined if the offending scenes were deleted or re-shot, but the film was released in Aug 1943 with Production Code Administration approval.
The bronze sculpture of Christine Dubois (Susanna Foster) was made by co-star Nelson Eddy, who was an accomplished sculptor.
In the scene where the three heroes escape the Phantom's crumbling lair (which involve the three characters running from a cave-in) only Susanna Foster appeared in the scene, the two male stars were deemed too important to film such a risky scene and had stunt doubles.
Stage 28, one of the oldest on the Universal Backlot, that was used for the silent version of The Phantom of the Opera (1925) and re-used for the sound remake of Phantom of the Opera (1943) was unfortunately demolished in 2015 to make way for major new attractions in the Universal Theme Park. The surviving Opera House set, also used in the remake and in many other classic films over the last 90+ years was dismantled and placed in storage. One of the oldest surviving sets from the silent era, its whereabouts are now unknown.