Plot hole: After they shoot the glass and McClane escapes, the terrorists all just leave. There are limited ways out of the room, there must be a blood trail over the glass, he's moving slowly...and they let him go.
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Suggested correction: Hans has no interest in John anymore; all he wanted was the detonators. It's not a plot hole, just a non-meta character decision. Sure, if they'd persuaded John, things would have worked out differently, but that's only obvious in retrospect.