Continuity mistake: When the "I LUV YOU" picture is viewed in Nordberg's hospital room, the photo has a vertical/portrait orientation. When Frank shows the picture to Jane, the photo has a horizontal/landscape orientation. (00:12:50 - 00:38:25)
Continuity mistake: When Valmont is waving the letter behind his back, in the closeup the address is facing upwards, but in the wider shot we can see the wax seal is now visible.
Continuity mistake: John Heard's racquet jumps from one hand to the other when he and Tom Hanks fight on the tennis court. (01:17:20)
Continuity mistake: When General Kael takes the baby to Nockmaar Castle, it has an extra 'turret' on the left-hand side, which has disappeared when Willow and Fin Raziel face the castle later on. (01:31:40 - 01:41:15)
Continuity mistake: The ruler in Tess' hands instantly changes design. It looks like she flipped it over between shots, but without any time or reason to do so. (00:19:20)