The classic gun mistake that wasn't.
In the climactic shootout, after shooting loads and loads of bullets, for dramatic purposes Stallone's gun finally runs out, and the slide locks back. This is normal. He then drops the empty magazine out of the gun, inserts a fresh one, and releases the slide. This action will take the first bullet off the magazine and load it into the chamber. At this point, the gun is ready to fire. But that's not dramatic enough, so after closing the slide, Stallone grabs the slide and yanks it back and lets it close again. You can see that first unfired bullet go flying away, wasted.
In this week's episode, an agent is being attacked by a cyborg, and after shooting him half a dozen times, the agent takes cover, pulls the magazine from his gun (Which already struck me as odd, since he should have had shots left, and the gun hadn't locked back) puts in a new magazine, and racks the slide, wasting the bullet currently in the chamber. He fires one more time before getting clobbered by the cyborg.
At first, I thought they were repeating the classic mistake, BUT, in a later scene, it's revealed that the second magazine had bullets that actually contained tracking devices. Suddenly, the gun-handling makes sense. He switched to trackers, and needed to get rid of the unneeded regular round.
About the only weak point is they seemed to be confused about the number of rounds fired and the number of rounds missing from the magazine, they either didn't account for the round wasted, or if he had "One up the spout" when he started.