In several scenes, references to deceased musicians and actors are visible. When Bruce Willis's character falls through the glass roof and lands in the pool, Jim Morrison can clearly be seen with a girl. Later on, an extra playing James Dean turns around (with his signature hairdo) as Willis steals his Grey Spider.
In the scene where Helen sits down onto a shovel handle, she didn't sit in the way she was expected to do, so the SFX people had to morph the image to make it look like the shovel handle was pushing up into her chest.
During the description of the plot to kill Madeline, there was a quick shot of the folder being stamped "case closed" at a desk. Also on the desk was a brain in a glass jar labeled "abnormal" - a tribute to the original Frankenstein.
Lisle climbs out of the pool after a swim and a manservant wraps her in a towel. She speaks one line, drops the towel, and is completely dry, even her hair.
When Ernest runs through ER looking for a doctor a short scene shows a CPR in action. On the ECG monitor a flat line can be observed, nonetheless the doctors try to revive the patient with an electric defibrillator. ECG flat line cannot be treated by defibrillation.
When Ernest falls from the Castle, he hits the glass face-down, but when he is shown from below, his back strikes the glass. (Due to a scene in which he sinks to the bottom of the pool, retrieves the unharmed bottle of potion, and then swims up which was cut due to the change in the ending, ending the involvement of the potion in the story.)