So I’ve had my glider for about two or so weeks and I was watching him play and noticed his back foot slide then I noticed that one foot looked different from the other. Not sure why or if I need to do anything about it.

Not really knowing your glider's history, it's hard to say. It could be due to a previous injury, or a deformity of sorts. Either way, if it's healed, not being infected or fussed with (animal not self mutilating) I wouldn't be so concerned. If you find its so bothersome, than you can seek a glider experienced vet..

On back leg he should have the 2 grooming nails you DO NOT trim and
the 2 climbing nail you do trim.
If nails are NOT trimmed he could get stuck and pull one off or caused another
injury.
hard to tell from picture but looks like first picture he had a past injury maybe.

No he has all toes one of the toes that’s supposed to be longer is around the same length as the shorter two

If say it was more of a birth deformity per say...the 2nd toe just didn't grow longer like it was suppose to.