About the only problem i've come across so far is something i'm going to have to check out on my next ME1/2 playthrough and that's the fan mission. in ME2 he acted like i decked him in ME1 but i was using my goody two shoes paragon character and he sweet talked the man down.
Ah, yes. Verner. It's not a bug. He's just goofing off at you to make himself look tough in front of the crowd. Full Renegade, he's dead. Full Paragon, he tells you that you shot him when all you ever did was pull a gun out for a photo shoot.