I don't know if the actors behave like this in real life, but every performance is contrived, pretentious, forced... including trying to break it with forced laughing, dancing, tricks...

Messages in the film are pro-war and negative, such as desensitisation to extreme gore (an autopsy with the persons face in the same shot, performed by doctors having a "loving" yet fighty conversation - this is early in the film to deliberately make it hard to walk out on, and big names in the film also encourage you to love & sit through it).

Characters only talk to each other as 'pretend fights' with no self preservation and preservation of relationships. Christian Bale is better at being a real person but you still can't care what happens to him.

Mike Myers plays a 'yes man' and any spirit he has is squashed by the script, screen play, and bad acting of all involved.