Audio problem: McKay is talking to Sheppard about the differences between himself and Rod, and at one point says that maybe Rod screwed up and was chosen for "a one-way ticket to another universe", yet his lips form the word 'galaxy'.
Continuity mistake: When the Atlantis team finds out that the experiment has caused problems in another universe, McKay's sister says to Rodney, something like,"You said that the chances of connecting to another universe that was inhabited were astronomically small." It was in fact Carter that said that.
Answer: Those are actually suits that protect from hazardous chemicals. They are cheaper for the prop department and look nearly the same as biohazard suits. A real biohazard suit would indeed have a helmet that seals to the neck.
Grumpy Scot