That safe?
Well, the stupidity of Elijah Wood's character in being so naive to think that the woman has nothing to do with the vault and that he could have gotten away alive, if she didn't use the phone, was one really irritating part that has been discussed a lot.
Now, let's talk about the safe. So, this is a secret criminal organisation with a vault full of diamonds worth millions (may be billions)and they do not even have motion sensors of any kind or vibration senors and heat sensors? I mean the second they breached the ceiling of the vault, there should have been a silent alarm and the whole movie should have been over shortly after.