The opening scene shows a carriage block with "Clarence Day" engraved on it. A few seconds later after the police man passes by, the carriage block has no engraving.
When Vinnie is ill, Dr. Humphries goes out and brings back Dr. Somers. When they go upstairs, Dr. Somers is going up first, but in the next shot he is behind Dr. Humphries.
In the opening scene, Mr. Day's milk canister swings too freely for it to be filled with milk.
The pocket doors between the parlor and the dining room have no room to slide back into what should be a wall, but is actually just a small space separating the two rooms.
Clarence Jr. tells Whitney some baseball news about the New York Giants. In 1883, the team was called the New York Gothams, changing to the Giants in 1885.
The movie opens "NEW YORK 1883". Later, Father rails at Mayor "Honest" Hugh Grant, who was mayor 1889-1892. Franklin Edson was mayor in 1883-1884. This is a holdover from the play, whose time frame is "the late 1880s".
There were several tunes used in the film that were written after the period in which the film is set (1883) - "Sweet Marie" (1893), "Love's Old Sweet Song (Just a Song at Twilight)" (1884), "The Treasure Waltz from 'The Gypsy Baron'";(1885), and "Daddy Wouldn't Buy Me a Bow Wow" (1892).
In the beginning, an elaborate clock is seen chiming. The clock has an arm that moves with each ring of the chime. The arm stops moving, but the chiming continues for several more tolls.
It's established that Clarence Sr. works on Wall St., which is located far south of the family home at 420 Madison Ave. When he takes the street car to work, he heads north on Madison.
In the beginning, as the boys come down the stairs, the maid appears to be among those who believe in one of the superstitions involving red-heads. However, she didn't seem to notice that both adults also are red-heads.
When Mr. Day is alone in the parlor while Vinnie is ill, he drinks a glass of water and then goes to give some water to the infamous rubber plant. However, he pours the water on a large leaf, and it runs down the leaf and onto the table top instead.