A non-critical oversight: A jack is required to remove wheels off a shopping cart which paints quite a funny visual in my mind, but can be a bit silly when you could just upturn the thing and use a screwdriver or wrench to remove the wheels.
Maybe add a special case for casters to not require a jack when mass is < a certain threshold?
Edit: … Although. http://i.imgur.com/umbIKad.jpg
