Same with me

The test cases return
[ 'Gap', 'gAp', 'gaP' ]
[ 'Hello', 'hEllo', 'heLlo', 'helLo', 'hellO' ]
[
'Two worlds',
'tWo worlds',
'twO worlds',
'two Worlds',
'two wOrlds',
'two woRlds',
'two worLds',
'two worlDs',
'two worldS'
]

I really don't see where the mistake is. Scratching head

I got that extra ' gap ' here without any capitalization. I'll try again tomorrow but I ran all the test cases in VSCode and they return correct result (definitely no extra words in array)

I cannot be absolutely sure, but it's quite unlikely that your code returns a different result in VSCode and here (though, there may be minor differences of implementations, but this doesn't happen often). Your code works fine on several tests, but fails on some others, you should focus on it and try to find where your code is wrong:

Should return: ' Gap , gAp , gaP ': expected [ ' Gap ', ' gAp ', ' gaP ', ' gap ' ] to deeply equal [ ' Gap ', ' gAp ', ' gaP ' ]

See there for a general help: https://docs.codewars.com/training/troubleshooting