I have had a few problems with collars in the past
I know how scarey it can be, seeing the kitty with the collar in the wrong place.
One of my cats had her paw and leg up in the neck area one day when I came home from work. I don't recall which cat it was, but that was the last time I ever put a collar on an inside cat.
Another time, I too, had a cat with the collar around her face and in her mouth.
I have heard of cats catching their collars on trees etc. that is why they have breakaway collars for cats. I guess when this was happening to me I didn't have breakaway collars on my cats.
They also have learned how to get rid of the breakaway collars....never to be found again....oh, and that includes an E-collar too. I have yet to find it. I think maybe Juni ate the E-collar. Just kidding.
I only put collars on my cats when they travel, incase they escape somehow. Now that I have four, I won't be travelling with them all! So no collars in this house.
I am glad you found the problem so early!