Post Hoc: because one thing follows another, it is held to cause the other 
Joint effect: one thing is held to cause another when in fact they are both effects of a 3rd cause 
Insignificant: one thing is rightly held to cause another but is insignificant compared to other causes 
Wrong Direction: the direction between cause and effect is reversed 
Complex Cause: the cause identified is only a part of the entire cause of the effect 

Smoking may cause an increase in air pollution, but it is insignificant in relation to the other pollutants.