Factual error: The sun can't rise out of the Pacific ocean when viewed from America, as seen when Danny is playing the clarinet. (00:01:20)
Continuity mistake: In the art studio Richie is working on a painting and it only has a small part finished. In the next shot the painting is completely finished. (00:08:25)
Continuity mistake: Several times in the art studio scenes Sonny's paint pallet is replaced with few paintbrushes and vice versa. (00:34:10)
Continuity mistake: The position of the roller skates hanging around Sonny's shoulders changes when he first enters the auditorium. (00:17:35)
Continuity mistake: As "The Fall" musical sequence begins, Sonny is seen skating along the Venice beach sidewalk. As he approaches the viewer we see people him around dressed in summer clothes and heat waves shimmer off the ground. Then in another cut the people on the sidewalk are now wearing long pants, heavy coats, and sweaters. It is also very windy. Then it cuts back to a summer shot again, and then for the last shots where Sonny discovers the Muse painting it's winter yet again. Obviously this scene was edited together from footage shot in two different seasons. (01:11:25)
Continuity mistake: During the scene where Sonny is chasing Kira to find out who she is, he asks two girls if he can borrow their moped. The scene goes from a sunny day to a rainy day within a couple of minutes. Then Danny shows up on the pier where Sonny falls into the water, almost as if he were waiting there for him. Sonny left him on the beach and chased after Kira - there is no way Danny could have gotten to the pier, much less knew where he was going. (00:14:00)
Audio problem: When Sonny arrives at work, as the Security Guards open the gates for him, we hear them chatting, but their mouths aren't open/are out of sync.
Continuity mistake: While pouring champagne at the end of a week of building Xanadu, Danny pours into Sonny's glass then goes to pour into his, when the camera switches mid sentence, Danny is filling Sonny's glass again. (00:58:25)
Continuity mistake: At the start of "Don't Walk Away" the rose blooms with nothing around it. In the next shot leaves and stems are right beside it. (00:55:45)
Continuity mistake: Richie's large painting stands in front of the stairs as Sonny enters. When Sonny leaves the painting is now beside the stairs. (00:08:25)
Continuity mistake: When Sonny first arrives at the abandoned auditorium and tries to open the locked doors, there are signs on the doors. Then the camera cuts to another shot of Sonny next to the sign, which suddenly has had its lower portion taped over. (00:17:00)
Continuity mistake: Sonny draws a picture, then rips it up and throws the pieces out of his window. However as we see the pieces sail through the sky, across the scene, they are all blank and white.
Audio problem: The tap dancing sounds during "Whenever You're Away From Me" are out of sync with their visual tapping.
Continuity mistake: When Sonny first sees the auditorium that eventually becomes Xanadu, the letters on the roof of the building that spell out auditorium are missing the A and R. Later when Kira takes him to the auditorium, the T is now missing. The following scene when Sonny and Danny arrive at the auditorium, the T is back. Finally, when Sonny and Kira are slow dancing in front of the auditorium before it magically transforms into the finished Xanadu exterior, the T is missing again. (00:16:30 - 01:03:10)
Audio problem: In "Dancin'" when we see the keyboard player playing, the audio doesn't match to what he plays.