I generally assume that every depiction of head injuries in movies or TV is going to be wrong, often dangerously wrong. I am rarely disappointed.
Hitting someone right over the top of the head (as in the chair over the head), with the blow aimed downward, is actually not a reliable way to knock someone unconscious. Kill somebody, yes; but to cause unconsciousness you want to move the head, not just hit it. That’s why boxers aim for the jaw; the blow flings the head sharply backwards and/or sideways, and that acceleration causes the concussion.
(Of course, if you hit anyone’s head hard enough you can make them too dizzy and pain-wracked to fight, but that’s not the same as a knockout. Also, they’ll eventually pass out, or even lapse into permanent coma, thanks to swelling of the brain, bleeding inside the cranium, etc… But this can take a while.)
Damn few people who’ve been knocked unconscious quickly regain consciousness, shake their heads a bit, and then jump up and resume fighting, shooting, running or whatever they were doing before they were knocked out. Even if they can, their friends shouldn’t let them, not until they’ve seen a doctor.
Unless a chair is already coming apart at the joints, it is unlikely to come to pieces just because you hit someone with it. Bottles, especially full ones, are potentially lethal. Even if they shatter, the blow can still do a lot of harm.
Don’t crack people on the head with gun butts, either. The gun may go off; you may damage the gun’s action; and you can fracture the person’s skull and do just as much prison time as if you’d shot him.