I have a full blown US visa and managed to travel to the US a couple of weeks ago where BA hadn't sent any of the information I'd inputted (and was saved in their system!). When I landed and went through immigration, I was asked by the TSA guy "hold, where did you come from? which flight?" as there was no record of me at all. No details of hotel, my visa info, nothing.

I was asked more questions than usual, asked to confirm my finger prints etc (luckily they were on the US system) and the TSA guy had to type it all in manually, but I was let through without additional questions such a a secondary screening - ironically that happened to the lady in front of me who had flown in from India.