Continuity mistake: When the next door neighbour brings back Toula's grandmother to her father, the camera angle from the front shows his right hand on her right arm near her shoulder. When the camera angle changes to a rear view, his hand is now on her shoulder. Happens twice during the scene.
Character mistake: In the opening scene where Toula describes her house, she says it is complete with "Corinthian columns." The columns on the house are of the "Ionic" style, not Corinthian.
Continuity mistake: Upon leaving their wedding, the couple are in a Cadillac limo. When the car arrives at the reception, it's a Lincoln.
Suggested correction: We see the car three times (getting in at wedding, on road, arriving at reception), and it is a Cadillac DeVille limo, about 1990 model year, in all three shots. Note the emblems on the hubcaps, tail lights and bumper.