Revealing mistake: When Johnny shows up to Cobra Kai dojo and all the kids are there. In the video playback they show on the phone you can see Miguel didn't land the kick, and the kid just fell down. (00:28:18)
Other mistake: Hawk gets a mohawk, but his hair was too short to style it like that.
Suggested correction: The mohawk was not a prop, but the actual hair of the actor they shaved off and mended together for him.
That is true, it was the actor's actual hair, but in the realm of the show, Eli's hair was not long enough to style that large of a mohawk out of it.
Continuity mistake: Johnny's car gets hit, and he comes up and starts banging on the windows. When the girls drive off, the rear window is down, when it wasn't prior.
Continuity mistake: When Johnny leaves his home to go to Daniel's place it's night time but when he gets there suddenly it's daytime.
Suggested correction: Daniel lives far away. Johnny must have driven all night.
That implies that Daniel lives like 5-6 hours from his job.
I actually assumed that it was already like 6am or something like that and knowing how sprawled our everything is there figured maybe it was like a 40 min drive. But then Daniel's wife also says it's Saturday morning yet Miguel and Sam are in school.
Other mistake: When Miguel and his friends use the restroom, he zips up after using the urinal, but there is no zipper on his costume when he turns around.
Continuity mistake: When Daniel threw his Crane Kick in the '84 movie, Johnny fell back and crawled away holding his nose as Daniel jumped around on one leg. But in the opening scene of this episode, Johnny is now prone on the mat as "Daniel" stands there in fighting position.
Strike First - S1-E2
Continuity mistake: During the pool party where Sam is hanging out with Yasmine and Moon, Yasmine holds her cup high in one shot but then low in the next.
Continuity mistake: While Daniel speaks with Cole at the car sales lot, the window of the truck beside them is up and down at least two times between shots.