I wanted to start listing rules I screwed up or that questions came up.  As a way for me to learn and to point to the wiki that is out there now.  Infinity is a very complicated game with lots of little rules.  I would say most of the mistakes I have seen were because someone didn't understand a rule.

The switch from 2e to 3e complicated things a lot.  The way VP are calculated switched and was pointed out by Ryan last event and I thought it was that way in 2e but not 3e.  Wrong there.

Plasma and Critical Hits:

I always played this as let my opponent take the crit against the worse save.  That is not the case:

http://wiki.infinitythegame.com/en/Plasma_Special_Ammunition

"Critical hits with Plasma Special Ammunition cause the target to lose 1 point directly from his Wounds/STR Attribute, bypassing the usual ARM Roll (the target must still make the BTS Roll). The effect of a Critical hit only applies to the target of the attack, and not to other figures affected by the Impact Template."

As you can see, pretty straight forward.

Retreat Check:

During my last game, there was a question if hidden deployed counts as dead.  The answer is they don't:

http://wiki.infinitythegame.com/en/Retreat!

"In game terms, each player must, at the beginning of their Active Turn, during the Tactical Phase, make a count of their surviving troops. For this purpose, consider any troops that have not yet been placed on the table (Airborne Deployment, Hidden Deployment...) as survivors. If the sum of the survivors' Cost in points is equal to or less than 25% of the points available for building the Army List, then that army enters a state of Retreat!."