Corrected entry: Dr. Phibes kills Dr. Hargreaves at a costume ball by crushing his head inside a frog mask. But one of the plot's main points is that Dr. Phibes is presumed dead following the car crash in Switzerland many years ago. So whose house is the costume ball at? If Phibes is presumed dead by all his friends and colleagues, why would they show up to a party at his house? Or did Phibes simply crash someone else's party, knowing (or hoping) that Dr. Hargreaves would be there?
Corrected entry: Dr. Phibes drains Dr. Longstreet's blood out of him while Vulnavia performs a violin solo. Later, when Dr. Longstreet's corpse is discovered and the police question his housekeeper Mrs. Frawley, she says that she heard a violin playing in the street "about half past 2 in the morning". But earlier, when Vulnavia was sitting outside playing her violin, it was broad daylight.
Corrected entry: Dr. Kitaj dies when dozens of rats enter his plane while he's flying it. Their biting and scratching causes him to lose control of the plane and crash. But before Dr. Kitaj gets in the plane, an airfield supervisor checks out the plane for him. How did the supervisor miss the stash of rats inside?