Walt returns home. He comes through the front door with a box under his left arm and dragging wheeled luggage with his right hand. One second and one camera shot later, the box & luggage are in opposite hands.
While in the box factory, Walt says the machine is a corrugator and explains how it works. The machine is actually a folder/gluer. You can see the folding rail in one shot. The building they are in is nowhere big enough for a corrugator machine, not including all the support systems that it needs.