When Maria is telling her daughter about her life in Greece and why she left, it is obvious that the audio has been re-dubbed.
When Toula's mother is talking to her on the phone while peeling potatoes, the sound of her peeling continues when she pauses for a brief moment at the beginning of the phone call.
The women wear their wedding rings on the left hand - Greek Orthodox women wear wedding rings on the right hand.
The Portokalos house has Corinthian columns which are said to be like those of the Parthenon. In fact, the Parthenon's columns are Doric, which are much older and simpler than the elaborate Corinthian columns.
In the wedding invitation, Portokalos is spelled "Rortokalos" in the Greek section.
When young Toula and her "friends" are in the car on their way to school, Gus' gloves disappear and reappear numerous times as he is driving.
When young Toula's dad drops her and her friends off at school, and stops her to remind her she "should be proud to be Greek", the window changes position throughout the dialogue.
When they are sitting on Toula's parent's couch, the plastic cover changes. One minute it is covering all of the couch, the next it is only covering the back of the couch.
Crew or equipment visible
When Toula sees Ian at the travel agency for the first time, a grey-haired man wearing a blue windbreaker is reflected in the window.
Errors in geography
A Canada-Post mail truck is visible in the distance, outside the travel agency window. For that matter, the Pappas Grill opposite the street is a well-known Toronto restaurant on Danforth Avenue.
In the Greek Orthodox Church there is an organ playing the wedding march. Eastern Orthodox churches are noted for their custom of eschewing organs or any sort of musical instrument at all.
In the English subtitle of one of the Greek verbal exchanges, "writing" is misspelled as "writting".
In the scene where Gus drives the three girls to school there's a black board visible on Toula's side of the car.