I think this episode raises an interesting dilemma: How can the Sliders morally justify cotinuing sliding when at *any* point they could carry a disease from world to another wihtout even knowing it? The history of European settlers infecting Native Americans comes to mind. They may be bringing new diseases to each new world they encounter. Of course, this is a conceptual nit and would end the series, but I honestly cannot see anyway out of it. Thoughts, anyone?
Oh, if we're going to pick reality-based nits here, what kind of power source does the timer use that they never have to worry about having the wrong kind of batteries, or the wrong sort of power to recharge the timer (if it's power cell is rechargeable) or end up on a primitive Earth for weeks where the timer's 'battery' would die?
And how are they able to pay for anything on any given world? There's no guarantee that the Earth they slide to uses the same sorts of currency that the Earth they left did. When they get jobs (as we have seen them do a few times), how do they show proof that they are who they are? Too many places - the mayoral campaign in one episode comes to mind - are very quick to hire someone for a fairly responsible job without having to fill out any sort of governmental paperwork that requires you to show identification.
And since keith brings up the question of disease, what about metabolic incompatibility? In an infinite number of Earth's, stands to reason they'd eventually come across one where the food or vegetation or something is poisonous. I know, I know, Beckett can't breath on Earth 'Prime', but even that was overcome when they made the move from Fox to Sci-Fi.
Ah, well, all in all still an enjoyable ride most of the time...
I have found the following nits:
First, the Protection Suits don't seem to be tight. There are several shots, where we see a doctor putting on his helmet without closing it on his neck.
Second, the Professor wants to heal Q with Penicillin. This only works against bacteria, but Q is said to be a virus.
The power issue is dealt with in "To Catch a Slider", in season five. As for bringing illness between dimensions, that is a major plot point in the later Kromagg related episodes.
Where is Q said to be a virus? Given the primitive level of medical technology on this world, I'd have a hard time believing they even knew how to tell the difference.