In Mechanic Sector (#81), you see these gears. One of which is obviously not turning the right way compared to how the others are turning. For the most part, the other 3 are turning together correctly, but the fourth one is just weird..
As you can see the gear with the green arrows are all turning together properly, but the gear with the red arrow is only turning properly with the lower green gear, even though it is also touching the higher green gear. This is incorrect.. obviously. The red gear is overlapping with the higher green gear and not turning with it, but against it. If it was actually within its indents so it turned with it, it would stop the higher green gear from moving because of the opposite forces coming together. They'd just push on each other. It also couldn't just stay behind it. 1) Because this is 2D people. 2) Because it would be able to go inside the dents of the lower green gear AND go inside the opposite moving higher green gear. Maybe a way to fix this is just take out the red gear?
This is a small error I found, but it really bothered me. Thanks!