Continuity mistake: Strange is at home, looking for help on a video chat. His friend says no, and in his rage he sweeps almost everything off the table including the Microsoft Surface laptop. Christine enters with food, we cut back, and the area of the table to his left, which was totally clear a second ago, now has several pieces of paper on it and the laptop with a closed lid. A few moments and cuts later, the laptop is in perfect condition on the table with lid open.
Continuity mistake: When Hong Kong is being destroyed, a vendor's sign falls to the ground, written in English. However, in the shot where the city is being restored, the same sign is now in Chinese.
Continuity mistake: When Kaecilius is attached to a wall just his hand is free, but in the next shot now his head and other hand are free too.
Continuity mistake: The wound and blood on Strange's left eyebrow is first fresh, then dry, then it's gone, then is back again.
Chosen answer: The airbag did deploy. However, the deployment occurred when the car first crashed and we see the accident from the outside, so we can't see it. Once we get a shot of the interior, you can see the airbag is sticking out from the steering wheel, but (unlike what some movies would show you) airbags deflate very rapidly after a crash, so you may have missed it.
But if the airbags did deploy, then why did he have such major injuries? Wouldn't the airbags have made what happened to his hands less severe?
I don't think so. I watched it again recently and I think I saw the car's speedometer crush his hands while they were still on the steering wheel, while the airbag deploys from the centre of the steering wheel, nowhere near his hands.
Often in real life, when air bags deploy from the steering wheel, they force the hands off the steering wheel resulting in the hands hitting the windshield. Damage to hands, wrists, and lower arms are common.