trek-tracks:

So people make fun of the Kirk shirt rip in Shore Leave because it is so blatantly independent of the fight with Finnegan

See:

then:

But what most people fail to acknowledge is that the Shore Leave planet is there to suddenly create things you are thinking about, rather than obey the laws of reality.

Which means that Kirk was thinking about fighting Finnegan, so he appeared:

Which also means, in the middle of the fight, Kirk must have thought: “Man, it would be so cool if my shirt ripped off right now,” leading to the inevitable:

So since we’re fairly certain now exactly what Kirk thinks about during fights, we can continue to laugh at his shirt rip in Shore Leave, but make sure it’s for the right reasons: not so much continuity error, more actually being Exactly In Character.