Sondra tells Peter Lyman that her father is having sensitivity in tooth "lower # 7." In the American tooth numbering system, number seven is always an upper tooth, specifically the upper right lateral incisor. In the British tooth numbering system, there is no tooth number seven.
There were several scenes where Scarlett Johansson's lapel mike radio frequency transmitter strapped on her waist behind her is visible.
Peter never asks Sondra how she got into his secure room to find the Tarot cards under the French Horn. (However it's conceivable he believed she saw him enter it when they entered the room earlier.)
The instrument in the Music Room under which the Tarot cards are hidden is constantly referred to as a "French horn" when in fact it is actually a Conn 16E Mellophonium. Additionally, in the first scene in which the Mellophonium is shown it appears without a mouthpiece. In all subsequent scenes a mouthpiece is in place.