Revealing mistake: When the Level 3 Sentry is firing up into the air for no apparent reason, it fires some rockets with a clear defined smoke trail behind them and disappear off screen. Then the shot jump cuts to further away and suddenly the smoke appears again, but the end of the smoke trails are solid and crisp indicating the animators used the smoke animation as if the rockets had just been fired from that spot... in the middle of the sky. (00:01:10)