Probably not. Good question, though.
The key is to do rotations that have some ACGME-affiliated program and GME office there. What you don't want to do is go to some outpatient doctor's office and do a rotation that you set-up on your own and expect to get credit for it. When you graduate, you will have to fill out paperwork for your initial license (in most states) that will make you list your core rotations and where they were done. I know I had to do this. And, they will check/question if something looks fishy.
-Skip