Originally Posted by MasterOgami
Its only seconds for the viewer, but possibly nearly a minute for Batman (I don't have a bootleg so I can't check). We see the close up of Batman in the cockpit before (and not even immediately before, as I recall) the last shot of the timer counting down (not the other way around as some have started to believe). So yeah, there's no timey-wimey weirdness or "magic screwy edit" going on in those moments, but there's also no mistake. Itís all rather straightforward:
-Bruce cables the bomb to the Bat with about a minute and a half remaining on the timer (I think, I'm sure someone can check.)
-Bruce takes it out over the bay. Close up shot in the cockpit.
-Unseen by anyone, including the audience, Bruce ejects. It of course happens off camera/between shots, otherwise the "surprise" at the end would be spoiled.
-the bomb's timer counts down its last seconds. At this point we can only guess how long the Bat's been on autopilot.
So while the editing definitely leads the audience into feeling as though Bruce was with the Bat up until the last seconds, it doesn't actually present that as what happened.
See, this is what I always thought. But I hadn't seen the film in a while and people started having me convinced that it went from the timer to Bruce. This is the most sensible explanation, and also the most simple.