When Bella is making the deluxe hot fudge sundaes for the boys, one of the cherries rolls off the top of the whipped cream but, when she sets the sundaes on the counter in front of the boys, both cherries are on top of the whipped cream.
Early in the movie when Bella is crossing the street, the movie marquee in the background has the name "Bijou" in the changeable part where the movie titles would/are displayed but above, where the real name of the theater is displayed vertically, it clearly ends in the letter "Y".
When Eddie is driving his sons to Grandma's, there is a road sign that says "American's" rather than the plural "Americans."
The movie is supposedly set in 1942 but some of the cars seen in the movie are post World War II models. For example, when Bella is hanging up laundry out in the yard.
Even though window air conditioners were sold as early as 1938, mass production, which lowered the cost, didn't occur until after World War II. It is highly unlikely that a house in Yonkers would have had two as we see when the gangsters get out of their car and walk to the store as Bella is making her "Johnny" announcement.