Corrected entry: It's been pointed out that McClane's shirt changes from white to green after he emerges from the vents; this is certainly a "cheat" by the wardrobe department to make him appear grimy and battle-worn. But notice, also, that toward the end of the film, the shirt switches back to white.
rbryant73
28th Apr 2003
Correction: Towards the end of the film he's not wearing a shirt at all.
tw_stuart