Corrected entry: Why does the blonde terrorist not understand Alan Rickman when he tells him to shoot the glass in German, but understands in English? Even assuming (as seems likely) that he just didn't hear him properly or else couldn't believe what he'd just heard, why would repeating himself in English make more sense, what with them being German?
Correction: They are not all German, as some of them speak German poorly, so English may work better for some of them.







Correction: It could be because when he says it in German, he says, "Shoot the window". The terrorist may have been confused and then he had to say glass to to him, but he chose to say it in English.
It could also be that he didn't understand the order. Honestly, under very few circumstances is an order to "shoot the window" or "shoot the glass" going to provide an advantage.