Continuity mistake: Axl and his friend chase Darren out of the house and into the snow, churning a path in the snow. However, in the overhead shots of all three boys, the churned snow path is not there, just undisturbed snow.
Continuity mistake: As Frankie excoriates her family for not noticing she was not on the train, her purse switches from her left to right shoulder and back again.
Operation Infiltration - S6-E18
Continuity mistake: In Mike's brother's room, the street sign above the bed changes from Main Street to First Street, then back to Main Street.
Continuity mistake: While Mike is explaining to Frankie his inaction to help Frankie, the red blanket draped over Frankie's shoulder goes from being on her shoulder, to off, then back on between shots.
The Answer - S6-E14
Continuity mistake: Sue's hands move around during the scene she is telling the family she got engaged. They go from by her face to The Table top etc even though there is not time for her to move them.
Flirting with Disaster - S6-E16
Other mistake: Brick says he heard Frankie say "Oh, great" when the phone flies out the car window, but by the time Frankie says that, the phone was already out the window.