Sorry but I was having a dumb moment. Actually, wasn't talking about offsets. Was talking about the third parameter, which lets you specify how many elements you want from the offset. For whatever reason, I missed in the PHP docs that it said that if the length is longer than the array, it just works up until the end of the array without throwing any error message. Markin' this one solved.
Actually, wasn't talking about offsets
No I know, that's why I mentioned 'from the offset' and that it (oversized length) will work with positive and negative offsets. I just added the note of oversized offsets.