The airplane door *spoilers*

I recently for some unknown reason remembered this movie out the blue, but my memory was a little inaccurate I think because I was young when I saw it.

I remembered that they were in the plan when the EMP went off. Then they walk around with the airplane door, which, I guess I presumed, was because it was fused to her arm by the nuclear blast. But in the this-or-that youtube clips, I see them each carrying it. So my question is - did they take it for some shade? Or to use as a kind of shield against radiation coming from the direction of the blast? I was not bothered by the lack of explanation, plus the karmic music tells you it's like poetry, and think of it whatever you want, but now that there's extended cut Bluray out there, I'm just curious... In the full directors cut is an explanation, and if so, what it was?

It's such an idiosyncratic, totally unexplained thing that makes this film instantly memorable to me, the kind of thing we used to get in "intellectual", artistic movies a lot... but now this type of thing would get cut because you can't waste time explaining it in the movie, and the audience and critics will complain.