Nail in the coffin? These were great shows... They aren't real, they may play with reality or reason a little, but jeepers... who wants to watch a great show and make it's coffin? I like to discuss the details too, but I don't share your attitude.
"Nail in the coffin" -- obviously failed attempt at humor in that so many people died because the bomb went off too soon.
I just find the timing things particularly funny because the show makes such a big deal about showing us the clock so often. So it was obvious when they showed us their clock and the bomb clock, and then later the showed us their clock when the bomb went off, and it was early.
To their credit, they never showed us the timer in Jack's hand, so we couldn't see what the timing was.
I had a little problem with the 2nd hour because it has to be believable to be really intriguing. If you can sit there watching and immediately think about what they should do next, and you would save them but they don't, I feel that this means the crisis is contrived and therefore less enjoyable.
Anybody can write a story where bad things just keep popping up, but to be truly entertaining it's best of the bad things, when they pop up, make you say "wow, I didn't expect that but it makes sense", rather than "I saw that coming, and there's no way that could happen in the real world."