Red Sky episode scenes where the sky isn't actually red

[Icebot]

As most of you may know, the last 3 seasons of the old TMNT toon were referred to as the Red Sky episodes. And the reason for that is because most of the time in those episodes, the sky is red, and it is always nighttime, and it seems the sun never comes up. However, there are a few scenes where the earth sky isn't red at all. Examples:

At the end of Enter Krakus, when Titanis gets banished to the prehistoric, the sky is blue like it's day time.

At the beginning of The Day the Earth Disappeared, the sky definitely wasn't red. It was a blue sky and it looked like the sun was about to come up.

At the beginning of Divide and Conquer, it's still dark out but the sky is purple instead of red.

[VaughnMichael]

Perhaps they are doing that to show what time of day it was?
Who knows really the old toon is full of all kinds of animation errors.