1.Sometimes, if your running companions and followers will always take the long way. Eg:If your running to Novac, boone will go around instead of the main entrance.
2.If your infront of the Gun Runners Vendotron and trade stuff with a companion or Follower and turn around you will be launched VERY VERY VERY High in the Air. Resalting in instant Death upon falling. (This one is actually only been found on Xbox)
3.At times, if your fighting a powerfull creature, Your companion or Follower will appear to lag and disapear, then re-apear about 30 seconds later. Usaually happens in Warped terrain or rocky areas.
4. If your follower is trapped in Ralphs "Special Inventory room" By it closing there is NO Way to get him or her out unless You talk to Ralph and re-open it. However at times if the Companion or Follower is close the door will not open and you cannot talk to ralph ever after this unless the computer notices it and cancels Ralphs script command and warps your companion or follower out.
5.At times when Lily goes into a mad rage state when "Leo" Says to go on a rampage and will not respond to your commands, she will stay in this state and never come out unless a save was reloaded or she is killed.