Did anyone notice once in a while Marykate and Ashley switch places being Michelle right in the middle of a scene? Like for an example, in the episode "Baby Love", Howie leaves. Then the next morning everyone comes up to check on her. Michelle says she wants Howie, and it was MaryKate. Then later when one of the boys took her out of the crib, it turned out be Ashley.
I'm not sure if I'm right or it's something else.

Well when they were younger they would switch out scenes in an episode because of child labor laws. Also, one might be cranky or something and not want to do the scene. I am not sure if they continued with this when the girls where older, or if they had them each do an episode. Anyone know?

In the one with Michelle playing soccer, sometimes the twin would kick with the right foot, sometimes with the left. Also,
I could tell in that episode the shapes of their faces looked
different. I don't know who was who, but one had a more angular face and was not as cute as the other one.

There's also the episode "The Hole in the Wall Gang" where D.J. is talking with Stephanie about why she is being copied a lot, and Michelle leaves. Then, a few minutes later, the other twin comes in with different clothes and her hair teased and done. It seems too quick for the Michelle character to change. I can't tell the twins apart, so I'm not sure who was who.

You're right...and how could "Michelle" fix her own hair that way herself?