When Nicholas Cage is seen playing an opera phonograph record, the turntable is clearly rotating at 45 RPM. With the exception of certain DJ dance records, the only speed that 12" LPs play at is 33 RPM. So the record was not actually playing. Instead, the sound was dubbed into the scene.
When Loretta is talking to Cosmo in the kitchen, we hear and see her tearing at the capsule on the wine bottle. In the next shot, we can still see the bottle and hear the tearing, but Loretta's hand is not there.
When Ronny and Loretta are talking about love outside Ronny's apartment after seeing La Boheme, Ronny is looking to the side. When they cut away, he's looking up. When they cut back, he's looking to the side again.
While at the opera during intermission, Cosmo orders a Canadian Club and ginger ale, and a Dubonnet on the rocks. While he and Mona are drinking, the C.C. and ginger ale isn't being drunk by either of them. Cosmo is drinking the Dubonnet, and Mona is drinking red wine.
Johnny proposes to Loretta at the conclusion of a leisurely dinner (complete with celebratory after-dinner champagne) in a crowded Italian restaurant that suggests that the meal is taking place well into the evening. Yet after the proposal, the couple still somehow manages to drive from Brooklyn to the airport, park and arrive for takeoff in advance on an international flight that is leaving at 9:30 pm.
When Cosmo is pouring champagne to celebrate Loretta and Ronny's engagement, you see Ronny holding Loretta's left hand with the ring on her middle finger. In the next scene, the ring is on her ring finger.
During the dinner scene with the "adults" Raymond Cappomaggi is seen with a front shot eating his meal with a fork in his left hand lifting the food into his mouth, and a glass of wine in his right hand. Immediately ensuing, the same scene is shown with the shot now from behind his left shoulder and he puts down his fork with his right hand.
In the beginning of the movie, as the La Boheme poster is being put into the glass display, the Premeire opening date reads November 15th. But the tone of the movie has already been set as "near Christmas". We have seen a man carrying a Christmas tree, and later we see Christmas cards strung in the dinning room on Cranberry St.
Loretta and Jonny leave the Grand Ticino restaurant, seen as being on Hicks St, which is in downtown Brooklyn. Loretta drives Jonny to the airport for his flight to Sicily, traveling via a tunnel. Since it's an international flight, he'd be going to JFK, but there's no need to travel via a tunnel from Brooklyn to JFK.
Loretta says "ti amo" to her father, and he answers "ti amo." "I love you" is the accepted English translation, but "ti amo" refers only to romantic love, and would never be used between father and daughter. They would say "ti voglio bene" instead.
When Loretta is leaving Ronny's apartment after saying she would go to the opera with him, he says to meet him at the Met. She comes back and asks "Where's the Met?". She took a cab, which of course would know where the Met is.
Clearly Ronny and Johnny Cammareri have been raised in the United States. They have no trace of an Italian accent and they have an established business in Brooklyn - the bakery. So how is it that their mother lives in Sicily?
Loretta goes to meet Ronny Cammareri at the Cammareri Bros Bakery. She is about to marry Johnny Cammareri, and yet she has never been to his bakery and never met his brother. Apparently she doesn't know her fiancé very well.
Loretta goes to the liquor store after returning from the airport and orders a bottle of wine. The male clerk says the price is $11.99 and Loretta hands him a bill which he gives his wife who puts it in the cash register. The wife hands the change to her husband who then hands two bills and a coin to Lorreta saying it was the change for her twenty. Even if sales tax was not disclosed to Loretta, two bills and one coin can not possibly make up the correct change for a twenty dollar bill.