Here are several rules that was covered during the other nights battle.
Damaging Squadrons 40k6 pg 77
To do this, allocate individual hits, rather than individual Wounds, one at a time, to the closest model in the squadron. Then roll for Armour Penetration against the correct facing (so against the rear armour in close combat) and determine the result of any glancing or penetrating hits.
Context: War Walker took a Crew Stunned result from Psyflemen shooting. Opponent wondered how the damage result would affect the vehicle squadron. The stunned War Walker couldn't move and could only perform Snap Fire. Other War Walker was unaffected. Per Abandoning Squadron-Mates 40k6 pg 77 vehicles that suffer Crew Stunned cannot be abandoned we assume, in this case, that its squadron-mates rally to its defense until a full recovery is made.
Accepting a Challenge 40k6 pg 64
If your opponent has issued a challenge, you can now accept it - nominate one of the characters in your unit to be the challengee. [sic] he can't challenge a specific enemy, just issues a challenge to the foe at large and see who steps fowards.
Context: Crowe assaulted Eldrad and friends. I thought you can challenge a specific character, nope. Shawn corrected me. Warlock accepted the challenge.
Night Fight 40k6 pg 124
If the Night Fight rules did not take effect during game turn 1, roll a D6 at start of Game Turn 5. On a roll of 4+, the Night Fighting rules are used for the rest of the game.
Context: We forgot to roll Night Fight at the start of the game. Turn 5 appeared and roll of 4, Night Fight was in effect for rest of the game. Shawn thought it was just one turn not the rest of the game.
Unrelated: Great story about the other nights battle. While playing this couple walked in. They were looking at some games nearby. The young lady asked what we were playing. Told her Warhammer 40k. She responded with genuine appreciation saying that it looked cool. Told her "When both armies are painted its great." Which Dave, bigwig at Fantasy Flight, was walking by and asked him "Dave isn't 40k better when both armies are painted?" Dave said it is better with painted armies than unpainted. She seemed quite enchanted by the models and table.