One bug was when i bought that ghoul companions contract, he went to shoot his former employer, but if this happend when the guy slept, nothing happend, well, not nothing, they started to talk, but he wasnt shot and i couldnt talk to the companion, not sure if i could talk to the bar owner, when i tried it while he was up in the bar, it worked. Another bug was with those cannibals, i went there at night and the first time i met them with that character, they stood outside a shed and said stuff that indicated they "thought" i had been in the shed, even though i hadnt.
Another bug was after i helped those BoS who has a rectuit, or something like that, i helped them out and they said they would help me if i was in the area. Later i left my house in Megaton and for some reason they were standing outside, but they ran away, i guess back to where you first meet them.