When Duvall is explaining his mathematical justification of why he believes the assault is warranted, he states that there are eight people inside the building, but at the time, he had no way of knowing how many people were inside the building, and this is verified later on when he asks Alex to tell him how many people are inside.
The camera zooms in on the bus right after the pill drop scene 1 hour and 20 minutes into the movie, the fire has been burning for some time in the bus but there is still snow covering the roof of the bus. The heat from the fire would have melted the entire roof at this point.