Once things have quietened down a bit after boarding, I usually take a quick walk towards the rear of the a/c to look at the door & see how it opens. (I check the nearest door forward as I walked past it)
On the last flight I took, one of the cabin crew asked me what I was looking at, so I told her. Strangely enough, I didn't get a strange look.
Mik
-- 20-odd years ago I was in a hall of residence which had a very minor fire. Seeing and experiencing the panic caused by the smoke was highly education.