Continuity mistake: When Troy and Rowsdower are standing and looking up at the Lost City that flies up and leaves the planet it is dark. But a few seconds later, while they are still looking upwards towards the city, it is full daylight.
Continuity mistake: When Rowsdower is fighting the two cultists that were to execute him in the forest, he falls and gets grass stains all over his white jeans. When he meets Troy in the woods a few minutes later, his jeans are much cleaner, and the next day all of the stains are gone.