Factual error: Melanthius claims to be friends with Archimedes, who died in 212BC. Yet the movie must be set after the birth of Mohammed, in 570AD, as it contains references to Islam. Only out by at least 783 years.
Continuity mistake: In the scene when Zenobia changes into a seagull, the gull has a pendant around its neck. When we see the gull in flight the pendant is gone, but when it lands it is back.
Continuity mistake: Just before the blue light from the shrine stops, Sinbad looks up and sees a large ice crystal fall, but in subsequent shots, you don't hear it land.