Up front, let me say I'm a big fan of CASTLE, but most of the characters acted, well,
out of character for this episode. All signs had been pointing to Montgomery the past few episodes dealing with this case, including his "retirement" scene just last week. Foreshadowing. But, I digress.
Montgomery - He made arrangements for the files to be found or sent, but knowing that he was most likely going to die, wouldn't he have given the name to Beckett at the hangar? (short answer: yes)
Beckett - Anyone truly think Castle would have been able to pick her up and haul her out of the hangar when her boss was about to be killed? Anyone think Beckett wouldn't have hidden and come to his aid at just the right time? Anyone think she would have fallen to pieces only to recover in time to see Montgomery die?
Castle - No way he physically picks up Beckett and moves her out of harm's way. First, she would have cold-cocked him with an elbow; second, he would have done anything to help her defend her boss. Third, he wouldn't let Montgomery face the killers alone.
Assassin (whose name escapes me) - He doesn't roll up wondering where Beckett is. He is in place already. He and his men don't clump together for convenient killing. And he doesn't let Montgomery get the drop on him at any point. Umm, these guys are trained (my guess is they'd be wearing body armor, too, and three head shots in the dark is unbelievable).
Finally, why kill Beckett? It's not like she's the only person who knows anything anymore. The entire office knows. The entire department would be rolled in now. Talk about shutting the gate after the cows get out. I realize this is TV, but this episode was just a bit too trite, too contrived for my taste. Better the producers finish this story this season, in this episode, then start something new next season, and that could have been the cliffhanger instead.