Julia should not be spazzing out. She should be seriously alarmed, afraid, rattled even, but... Then again, maybe the whole situation is crashing in on her, after she took on such a dangerous project with Barnabas in '67, and it's worn her down. She started out supremely confident, but all the conflicting feelings and loyalties and morality have over time shredded her nerves, understandably.
The blooper of all time is in this ep., and I saw it before hearing any fan mention it, so I thought I was hallucinating, seeing this for the first time as an adult a few years ago.
Much of all this drama is unnecessary... all Lang had to do to quiet Julia was to tell her up front, from the beginning, that he could go back to using dead parts to finish the creature. Julia contradicts herself for the sake of cheap drama, first saying she won't tell, then saying she'll do everything she can to stop the experiment, before going out the door. And Lang doesn't get the gun out again, for some reason. Seventh mention of the word "vampire", by Julia... should I stop counting now?
Barnabas sputters out that Ang could be destroyed by "catching" her at a crossroads, in the dead of night. They actually throw in an acknowledgement, if not an explanation, of Ang not controlling Trask in 1795, because "it wasn't safe at the time". I guess they were afraid that the question was about to pop into the viewers' minds. Actually, it all was working out for her, without her having to control him. Peterson doesn't recognize the name of Trask, so maybe he isn't a descendant. Good for him, refusing to kill Lang, even in a trance.