pitfall

Short definition from Wiktionary

Noun

1. 1
   A potential, unsuspected, hidden problem, hazard, or danger that is easily encountered but not immediately obvious.
2. 2
   A type of trap consisting of a concealed pit in the ground, which the victim is supposed to fall into and not be able to get out from.
3. 3
   An antipattern.
4. 4
   Subsidence below ground in a mine, which can cause the ground level above to drop.