A blender jar and its motor base need to travel apart, since the glass jar is the fragile half and the base is the heavy half, and knocking together is how a blender chips or cracks.
Pro tip: Save a spare rubber gasket or seal ring if your blender uses one; they are easy to lose and hard to replace quickly.
Watch out: Never pack the jar still attached to the base; the connection point is exactly where cracks form under the weight and vibration of a move.