On the first one - I'm guessing that, because the actual motion of the mandibles emerging would be pretty much impossible to show, the "mandibles jutting from its mouth part" should be seperated to be make it more clearly describe a current condition of the body, rather than coming right after a description of action. Would that fix it?
On the second one - I'm pretty sure that the description of Mike walking around the counter is making it seem like too much movement, because he can only be shown at one point in relation to the counter. Is that right?
Jumping slightly off-topic for a second:
Did you receive the script excerpt I sent? I don't think I messed up any of the rules, but I didn't hear back from you like last time. Just wanted to check.