Goofs

When seen from various angles, the "disembodied hand" seems to have different lengths of wrist attached to it. When seen in wider angles (usually shots in which cast members interact with it) the hand seems to have an inch or more of wrist connected, but when seen in close angles (such as when it is playing the piano) it appears to have been severed much closer to the palm.

The handprint outside the mausoleum lacks a mark for the ring that Ingram wore.

When Hilary is in the library, he empties shelves of books looking for the 'hand'. In following scenes, when Raymond, Donald, and the Commisario, as well as when Julie and Hilary are in the library, all the shelves are full of books.

The Commissario says he has found fingerprints less than a day old. Normally there is no way to date fingerprints.

The human forearm contains two bones, the radius and the ulna. At the level of the wrist, the radius has a larger cross section than the ulna, and the radius is nearer the thumb. When the disembodied hand is strangling Hilary, the smaller cross section (ulna) is nearest the thumb.

The handprint in the soil outside the mausoleum is not a print. A print would be pressed into the soft soil, but the handprint shown is in relief (raised above the surface). Hands or feet don't make that kind of impression.

When Julie is opening the door for Conrad when he first visits Mr. Ingram, the shadow of the camera can be seen following her to the door and back to Mr. Ingram.

Conrad requests of Julie that the two of them leave Italy without the Commissario's knowledge. He should know this is impossible as he saw the Commissario confiscate Julie's passport sometime earlier.