Certain vertices aren't parented to rig. How do I fix this?

Support Animation and Rigging
1

For some reason, when I move a leg, half of the leg stays in place. I don’t know if all the vertices are properly assigned.

Here’s the link:

Thank you

2

I think you’re right. First go to pose-mode to stretch the rig into a pose so you can see all the stretching problems, then, with the rig still selected, go into weight paint and paint out all the vertexes that are left behind to the right bone.