Totally expected - standard sprite behaviour when edge bouncing
As expected - arm can't wave if it not able to rotate
I'm assuming this is the one that you want to actually look OK?
If so try this out
Basically arm sprite checks the direction of alonzo sprite and alters its own direction and flips it's costume vertically
FYI When someone else opens your projects - it opens up in their editing mode not yours
[edit2 -slightly simpler]
A visually better method is to leave arm sprite script alone and alter the alonzo sprite
This alters the direction and flip state of the arm sprite when alozo sprite turns around and avoids the slight lag the previous method has but is a bit more complex
I did the car spinning wheels example suggested by cymplecy.
Initially, when it turned at the wall the wheels shifted position. Then I altered the pivot point of the car to be horizontal (and half way between the wheels) with the pivot point of the wheels, at their centre. This solved the problem.
I also reset the spin direction of the wheels to correlate with the car direction. It also works fine if you change the size of the car. Snap! car_spin_wheels (berkeley.edu)
I think this sentence in the manual, p. 10, is incorrect, "The precise place where you let go of the mouse button will be the attachment point of the part on the anchor."
What worked for me was placing the wheel part in the correct position on the car before dragging that wheel from the sprite corral onto the car.