Audio problem: When Tori and Kwon are talking in the hotel lobby, Tori says, "Maybe you shouldn't have let him kick your ass," but as she turns her head, her lips aren't moving.
Revealing mistake: The scene where Johnny is assembling the baby's crib in his apartment while talking with Carmen; they share a hug as the camera pulls back, and you can just make out the outline of the pregnancy pillow the actress is wearing under her flowered dress.
Continuity mistake: In season 2, when Johnny is telling Miguel about the birth of his son, Robby, Johnny says Robby was born in 2002 and that it happened shortly after the death of his mother, Laura. In a flashback during the final episode, however, we see Johnny visiting Laura's grave, and it says she died in 2007.
Answer: Just like in the original film, some guys want that brutality. Johnny in part opens the dojo because of his past rivalry with Daniel and to train a kid that's being bullied. But also, other kids that are being bullied want to join in order to learn to fight back. Johnny is also teaching the Cobra Kai creed (Strike First. Strike hard. No Mercy.") so that's why he opens his dojo with that name and the old Cobra Kai dojo's past reputation is exactly what he wants to elicit.
Bishop73