The latest behind the scenes video shows that the shot of Bond and Madeleine talking as the crater lair blows up is real. Maybe I'm a cynic, but I assumed they had been added over a blue screen of the real explosion.
Oh, really? I thought that they were a bit unimpressed by the huge bang, despite being so close to it. Also, I noticed no signs of a blast wave. That's why I. too, thought it was blue screen.