Continuity mistake: In the scene where Roger and Hoskins are moments away from crashing into a bridge in the cab quickly look at the road there is no gate in between the roads. But when they jump onto the bridge they crash right into a gate. (00:57:15)
Continuity mistake: When Kristen meets the little girl drawing the chalk house, between the two shots before it starts raining, the chalk drawing changes. (00:02:35)
Continuity mistake: When Mac's on the windshield and the car starts to dodge cars, one shot from inside the car shows the alien has disappeared.
Continuity mistake: When Delia spray paints the word “mauve” on the wall, between shots it is apparent that the script of the word changes. One example would be that in the first shot the tops of the letter “M” are pointed, like triangle tips, but in the next they are more rounder. The writing also moves lower on the wall. (00:15:50)
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)
Visible crew/equipment: When they're building the petticoat balloon, the camera slowly goes back. Look at the lower-right corner of the screen: there is a man wearing a stadium jacket. He's a crew member.
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: In the scene where Bill's old boss comes back to see him notice when Bill shoots him and takes the drink. All of the drink comes out of his chest because of the bullet holes. Well notice his shirt is all wet, then in the next scene when he takes off his hat his chest is all dry.