In Second Edition there were critical misses. These were caused when you made an attack roll and the twenty-sided dice would naturally roll
a value of one. When it happened to players it was a chance for DMs to introduce an element of controlled chaos into the game, and when it
happened to a foe of the PCs it was a humorous occasion and opportunity for players to quickly doom their clumsy opponent. Whether the
weapon dropped or merely wedged tightly into the side of a nearby tree, critical misses were often more entertaining than critical hits
and they rarely caused direct harm. A critical miss didn't result in cutting off your own foot or the accidentally bashing head of a comrade.
In 3rd edition D&D, critical hits are a simple mechanic. When a 20 or some other number within the weapons
critical threat range is rolled, then the player rolls again. If they "hit" with the second roll then it confirms the critical attack and
extra damage is dealt.
When Does a Critical Miss Happen
Critical misses are even easier since there is no "critical miss threat range." A player only risks a critical
miss when they naturally roll a 1 on their attack roll. When this happens, roll a second attack roll to confirm the critical miss. If
this second attack roll also misses target opponent then a critical miss is the result. This means that skilled characters are less likely
to critically miss weaker opponents, while more difficult opponents increase the odds of confirming a critical miss.
Critical misses only happen with manufactured weapons, never with natural weapons or with spells that are
treated as weapons.
The Effects of a Critical Miss
When a critical miss occurs then two things happen. First, the attacker loses any remaining attacks for that round. Second, they
must spend a move action to recover from the critical miss on the following round. This move action is typically something like picking
up their weapon, dislodging it from a tree, disentangling their weapon arm, drawing another weapon, and so forth. Recovering from
a critical miss often grants opposing foes an attack of opportunity.
DMs who want help deciding what happens when a critical miss occurs are offered the following solution. If the
confirming roll was an odd number then the weapon was dropped in the attacker's square or in a random neighboring square (use a scatter dice
or simply roll 1d8 if you really want to be random. On an even roll, the weapon became stuck in something: a log, a tree, the ground, or
whatever is nearby.
In my own campaigns, critical misses never result in direct damage to the attacker or their allies.