It was ingenious how they did the snow effect. It is mostly paper. The Bastogne scenes were shot partly indoors so it requires the actors' ability to communicate how cold it is. I learned all that from the bonus disk of the series that has segment called The Making of Band of Brothers.
Every personal war story I've read about veterans of the Battle talks about the cold. Often with comments like, I swore I would never complain about a hot summer day again.
Crews Now Feel Safer -
——Another danger that has just about been licked is the problem gun-blister blowouts when the cabin is pressurized. Such blowouts have hurled the gunners off into space and usually to death. New methods of mounting the blisters has eliminated the possibility of blowouts.
A little more info here: http://www.aviation-history.com/boeing/b29.html
Some problems were solved other than technology. Cooling issues were a major part of lower bombing decision?
The major factor in creating an efficient bombing machine out of the Superfortress was an Air Forces Major General named Curtis E. LeMay. Nicknamed “Iron Ass”, LeMay was put in command of the Marianas based B-29s and was responsible for solving several of the Superfortress and operational problems in one stroke: He ordered the B-29 crews to remove the guns (the tail guns were replaced with broom sticks so the enemy fighter pilots, hopefully, wouldn’t become aware of the missing guns). Also the gunners and all the ammunition were to be removed. And he ordered the missions flown at 8,000 to 12,000 feet. Bombing accuracy had been miserable because of the high winds at the 28,000 to 34,000 foot level where previous mission had been flown. Aborts were common because of engines which overheated in the process of climbing to which altitude. With the new procedures, fuel could be saved, without the weight of guns, ammunition and gunners, more bombs could be carried, engines would run cooler and bombing would be done from below the fierce winds raging over Japan.4