In the scene where Richard and Julia enjoy a bath together, where they discuss his hating his father, rewind to just before this. As an intro to the scene they show a toe (Richard's or Julia's or a stunt double's) playing with the faucet of the bathtub. During the scene, the faucet is behind their right shoulders.
If you had paid close attention to the first part of the movie where Julia Roberts is taking a bath and singing and then Richard Gere comes in and he asks her to stay for the week, there's a backup shot of the two and you can clearly see that the tub has two faucets instead of just one. So, no errors were made during the shot of the two in the tub when you thought that the they had the toe shot at the wrong end.
You obviously need to watch the film more carefully. If you watch the scene where Vivian is singing in the bathtub, you will notice there are two faucets. One is at the top of the tub and the other at the bottom.