Rewatched this episode today....I loved it when Barnabas got the upper hand on Will. Will treated him horribly, as Robin pointed out, especially since he considered Barnabas his stepping stone to reclaimed fame, fortune and glory with a most interesting, if partially, dishonest biography. The biography that Will was writing was the RT Barnabas', but Will planned on passing it off as the PT Barnabas'.
Would have loved it if Carolyn had been in this episode. Would she have enjoyed seeing her husband's schemes literally go up in flames? She probably would have gotten some small measure of satisfaction of him now being under the vampire's power since he had ridiculed her mercilessly over her experience as Barnabas' victim.
I agree that Barnabas probably did figure that he could get back to his own time like that, thus why he could care less whether Quentin is suspicious of him or not. I always wondered though why he didn't just 'appear' in the room without having to ask for anyone's permission....just wait until someone isn't there, sneak in, and wait until the room changes. If someone comes in, hide, or transform into a bat and get out of dodge and try again later.
I mean, I doubt very much he still has Petofi's 'unable to vanish' mark on his hand, that was awhile back.