Continuity mistake: When Jax and his crew meet up with a Hispanic gang to sell them guns and are outnumbered, they run in the station wagon. The run the station wagon through a gate and roll it, destroying the front end, but magically the station wagon's front end appears with little damage afterwards.
Other mistake: Abel was 18 months old when Thomas was born. All through the series, Thomas hardly ages. In season 7 Abel is 5 and in kindergarten yet Thomas looks younger than 3. He's not even walking or talking yet! Thomas should be at least 3 years old according to the time span of the series.
Character mistake: Tig gets bit on the right butt cheek. Tara tells Chibs to give him a local, which is a numbing injection so she can stitch him up. Problem is that Chibs does the injection in the left butt cheek. You are supposed to give the injection close to the wound to numb it before stitches.
Character mistake: The nurse that was helping the doctor tend to Clay has blood all over her gloves. As she leaves the room, she takes off one glove. No hospital anywhere would allow doctors or nurses to roam the hall with bloody gloves and hands. It's a health hazard.