Won't get into anything concerning the bus (as Roger Ebert said concerning the freeway jump, this is a movie where you don't ask those types of questions), but where the heck was Jack heading atop the train? Especially with Payne in the car before the motorman's cab (which Payne had a good view of), there wasn't anywhere Jack could sneak into and catch an armed Payne (with a dead-man's-switch bomb to boot) by surprise.
The entire train sequence doesn't make much sense, seeing as how subways can be stopped remotely by simply killing the power.
Also, Harry is walking with a cane during and after the award ceremony - but the very next day he's perfectly capable of running?
It's implied that some time has passed by between the first act and the main act. Jack is taken by surprise at the mad bomber coming back at him, and it assumedly must have taken weeks for Payne to put his diabolical plan in motion, unless he had already set it up as backup plan for the elevator job.
Although this troper has always linked Harry's hangover in the station with the one he received at the party. Plus when Jack gets his coffee it is explained that 'he was up all night partying'.
Fair point, but as is said above Jack is taken by surprise when Payne calls him on the payphone, plus later in the film when Jack is explaining what's happening to Annie he says that "a while back" Payne held some people hostage. Incidentally, even if some time has elapsed, it's still possible Payne was working on the bus job at the same time as the elevator job in case the latter failed as one of the above tropers said. After all, he said he spent two years preparing the elevator job, and it is almost certainly not two years later when the rest of the film takes place.
Awards ceremonies don't happen overnight. It could have been the better part of a year before they received their medals. So everyone is correct in that: A. Lots of time has passed and B. They are all hungover from the awards ceremony.