Since non-vital CAN traffic is silenced during this process certain items may not work while flashing. This includes the door mechanisms as well as the windows. If you find yourself locked in the car in an emergency and need to get out, there are mechanical emergency straps located near the door, over your shoulder. Give it a yank and the door will open. This is good general knowledge to know in any emergency while operating a McLaren. Flashing with the door open or windows down will not cause an issue.