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Continuity mistake: When Rey is shown for the first time while undergoing training in the forest she falls to the ground face-down. When she gets up her clothes are soiled with dirt as expected, but in all shots after that, in the same forest sequence, her clothes are perfectly clean again.
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Other mistake: During the lightspeed skipping sequence, there is a scene where two Millennium Falcons appear on screen.
Suggested correction: These are mirror spires, a reflective surface. It's not a mistake.
It was confirmed to be a mistake in rendering. The "mirror spires" was made up to try and excuse the error.
No, the director actually said that this was a planet that shows reflections. Because you can see the towers reflected.