In the second short, Rex turns Hand-in-the-Box's handle multiple times until the hand finally pops out and scratches Rex's back.
In the third short, Hand-in-the-Box and Rex are seen on the desk beside each other. Hand-in-the-Box pokes Rex on the back and moves the hand away when Rex turns his head around. Hand-in-the-Box pokes Rex on the back again, and Rex turns his body around to see who's there. Hand-in-the-Box orbits him out of sight, until Rex's tail knocks Hand-in-the-Box off the desk.