In the part where you collect 4 keys, when you collect a key Madeline is transported back to the start in a bubble. Her hair in the animation is the wrong color, it should be red but it was pink.

I might be intentional, because water is blue and bubbles are water, so colors would be slightly blue-shifted

In previous chapters, Madeline goes through the same bubbles after collecting B-sides, and her hair is red.