Ethan Hunt: I can't get to the roof!
Declan: Where are you?
Ethan Hunt: Look up! Look up!
When Tom Cruise is going to defibrillate Keri Russell to disarm the bomb in her head, no defibrillator takes 30 seconds to charge to 150 joules. Most go to 360 joules and if they are not charged in 10 seconds the batteries are depleted enough that they won't charge at all.
The scene in which Julia brings Ethan back to life is copied almost identically from the scene in "Lost" (Director JJ Abrams' hit TV show) where Charlie is brought back to life. Incidentally, you can hear the "Lost" music played throughout the show, most noticeable when Davian is about to pick up the gun to kill Julia.