Kubo is told in his dream to "follow the setting sun" in order to find the helmet. He immediately wakes up and leads his group into the rising sun. Then the shadows indicate light is behind them, then in front again.
When Kubo flies upward to return home he is missing his sword. When he lands, his sword is at his side.
Kubo is trying to speak to his ancestors when using the lanterns. The light is behind him, yet there is also light shinning directly into his eyes from a source in front of him.
On the afternoon of the village festival as Kameyo is talking with Kubo, the wall behind them has a large round shadow of a paper lantern which isn't there.