Quotes: Obvious Rule Patch

A summoned monster cannot summon or otherwise conjure another creature, nor can it use any teleportation or planar travel abilities.
— Summon Monster I spell description, Dungeons & Dragons 3.5

To put the matter beyond any shadow of a doubt - only Orcs on foot benefit from choppas - not Goblins, not mounted Orcs, not models on chariots, not small boys named Kevin, not Gerbils, not anything else, never, not ever, OK!
Warhammer Armies: Orcs and Goblins (6th Edition)

Black Hat: Turns out most colocation TOSes don't mention beehives.
Megan: I suspect that will soon change.
xkcd 1439, "Rack Unit"

Additionally, look for rules that stand out to you. Especially things that are oddly specific or that address edge cases. These sorts of rules almost always come out of testing. They tend to be a patch for something that the designers found after the initial design was complete. See if you can figure out why these rules were necessary. Why the game would break down or how players would exploit the game if those rules were missing.