Continuity mistake: In the last scene, the Butler and Groomsman load a Sarcophagus in the back of their station wagon. The tail gate is left open and both step back as the vehicle pulls out. As they are driving off down the driveway the tail gate is closed.
Revealing mistake: When the private eyes enter the mausoleum it is well lit from the studio lights when it should be pitch black as they enter.
Continuity mistake: Throughout most of the film it is night-time, but 3/4 of the way through a backdrop of the estate is dusk.
Other mistake: It is night-time when Dr. Tart (Conway) releases the 2nd dove out the window. Moments later we hear 2 gunshots and a plop sound of a dead bird. Which would be impossible as the shooter could not see a gray bird in the night sky.
Revealing mistake: When the private eyes are outside on the grounds there is loud thunder and lightning but it never rains.
Continuity mistake: When the pair fall out of the chimney, Mr Uwatsum, lined up on screen left, has his left hand gripping the hilt of his sword. Switch to Phylis entering, his hands are by his side.
Continuity mistake: When the pair fall out of the chimney, the right, front paw of the bear rug left of shot can be seen. The shot cuts to the lined up staff, where Mr Uwatsum is seen actually standing on the same paw.
Continuity mistake: In the scene where the work crew is getting introduced (after the inspectors fall down the chimney) Hilda the maid already has Tim Conway's business card in her bosom before he gives it to her.