The 'what this gun can do' scene
I think it was a mistake to have the main villain "explain" to the hostages how deadly his weapon is. Somehow, it makes him look less dangerous. It's as if he needs to reassure himself (and the passengers) that he indeed has a deadly weapon, when you can just LOOK at it and know that it's far deadlier than a handgun.
It's like the old "don't mess with me, I am a Black Belt in Karate" ploy. NOBODY uses that anymore (if they ever did?) because it's nothing but talk. If you are a real tough guy (in this case the head honcho) then there is no need to verbally let people know it. Especially since you are holding a big gun. All you need is body language and a facial expression (which he already had in droves).
Yeah, the whole spiel about how powerful the weapon is could have been left out completely. It is unnecessary.