Alias

Sydney asks Jack to tie her up, which Jack does. Yet Jack, who is a trained CIA professional and veteran, elects to tie her hands together in front of her, which is one of the least secure ways of tying her up. He should've tied her hands behind her to better immobilize her.

Not real a goof, but when the teacher said. "Het is grappig. Begrijp je. Vertel hen: 'Het is grappig.'" I could not understand what she said and I am Dutch. Sounded like she put the words through a meat grinder. Sydney said it a bit better. Like I said more of a comment than a goof. The person sounding Dutch was the girl in the classroom answering in English! The teacher really messed the pronunciation up, and yes, Sydney did a bit better.

The flat in Amsterdam clearly has US light switches and power sockets, not Dutch ones.

How does Vaughn know he's found the antidote? All we see is him rummaging through a disorganized lab and picking up a test tube. Even if it was labelled (as what, "antidote to bad batch"?) wouldn't the label be in Czech? Just how many languages do Vaughn and Sydney know?

The scar on Sydney's neck consists of two punctures. That makes sense if you're thinking of vampire fangs, but would ordinary human teeth leave that pattern?

Goof: When Sydney crawls into the crawl space in the beginning she goes to "pick" the lock on the door. The camera flashes to the lock snapped shut but when she inserts her "tool" into the keyhole you can see it's already unlocked as she even turns it and opens it a bit.