Misrouted Reserve Pin
A senior parachute rigger discovered this incorrectly closed reserve container during a gear check of another jumper. The reserve ripcord was on the wrong side of the grommet, and the reserve closing pin was flipped opposite of the correct orientation. If the jumper had to pull his reserve ripcord, the result would have been a harder-than-normal or maybe even an impossible pull. (However, the RSL or AAD would have been able to activate the reserve.) An FAA Master Rigger had just packed the rig, and the rig owner took it back to the rigger to be repacked and closed correctly.
Packing errors from parachute riggers are rare, but they do occur occasionally. Rig owners should understand their parachute equipment well enough to recognize when there is a visible mistake in the closing of the main or reserve container.