When Guido and Claudia go out for their drive, they stop near some springs. Guido exits the passenger side of the car (off camera); we hear the door open and close. But when Claudia, who was driving, steps out moments later (also off camera), we never hear her door open or close.
When Guido visits the cardinal in the mud bath, the cardinal is sitting in a chair, fully dressed in his cassock, as two attendants use a sheet to form a curtain around him; however, as the camera cuts to a closer angle, the cardinal is suddenly undressed to the waist.
When Guido visits Carla during her illness, a strap of her slip disappears in the close shot after she rolls over, but is apparent in longer shots both prior and after.
A man tells Guido that he has placed something in his right-hand pocket (a gun), when he goes to shoot himself under the table, he pulls it out of his left pocket.