Goofs

At 1:57, Lydia walks down the hall wearing neutral colored hosiery. But when she walks into Professor Hunham's classroom, she is wearing opaque white hosiery.

When Angus is skating on the Boston Common ice rink, his jacket front is covered with ice shavings before he face-plants and clean after he gets up.

When Paul Hunham learns from Dr. Woodrup he will be monitoring the holdovers, Woodrup's fountain pen jumps from side to side of his paper.

During the chapel scene, the blinds of the swell box on the pipe organ switch between being open and closed in cuts between the priest and shots from the balcony.

After Hunham has set the plate of cookies on the table, Angus excuses himself. The next shot has the arrangement of the cookies on the plate altered without any person or reason to have done so.

After Paul finds a bottle of Angus' Librium (chlordiazepoxide), he points out it's for depression. In reality, Librium is predominantly prescribed for anxiety with no connection to the treatment of depression.

Jason's father arrives to pick him up in a 1979 Bell model 206B. However, his father is the head of the parent company of Sikorsky Helicopters, so it is unlikely he would be flying in a helicopter made by their chief rival. (Sikorsky was sold to Lockheed Martin in 2015)

Tully dislocates his shoulder, a painful condition that requires weeks or months of rehab before the shoulder is back to normal. Yet he is out of his sling, carrying heavy items, obviously completely unimpaired within a couple of days.

At the Christmas Eve party, an aluminum tree is part of the decorations, with a string of electric lights on it. Aluminum trees were almost never strung with electric lights, due to the chance of the tree shorting out the circuit breaker. They were typically illuminated by a "color wheel" light, projected onto the tree from the floor.

The composing credit for the Christmas carol "Carol of the Drum (Little Drummer Boy)" is incorrectly credited as "Traditional". It was composed by Katherine K. Davis in 1941.

Hunham's "lazy eye" moves back and forth between the right and left eye. This has been revealed as intentional.

Hunham orders a Jim Beam on the rocks, and is served a double Jim Beam, no ice.

However, when Lydia delivers his drink, she says she made it a double without charging him.

Some songs on the soundtrack were released well after the December 1970/January 1971 period of the film. They are for the audience's benefit, and not heard by the characters, unless stated otherwise.

There are several outdoor scenes set in snowy, cold winter weather, but no breath vapor is visible as characters speak or exhale.

When Paul and Angus go to the "packie" (liquor store) in Cambridge, the sign on the front shows open hours on Sunday. In 1970, Massachusetts still had "Blue Laws" that forbade liquor stores to open on Sunday.

At 96 minutes in, Paul Hunham and Angus Tully are walking on a street in front of several Boston shops. An Apple iMac computer can be seen in the shop window.

In the skating scene in Boston park, the Christmas lights in the background are LEDs, which are not used in Christmas lights until year 2000's.

Around 89 minutes in, Hunham tells the "candy cane" sex worker that he's pre-diabetic. This term entered the language in 1997.

Around 1 hour 24 minutes into the movie, even though all cars on the highway are from older times, you can easily see a row of modern vehicles parked along a side street behind the separation wall of the highway.

Hunham talks about the three-year siege of Carthage during the Third Punic War and concludes by saying that this is where the term "punitive" comes from. The word "punitive" derives from the Latin verb "punire", meaning "punish". This is etymologically unrelated to "Punic", which instead shares its origin with "Phoenician" (Carthage was founded by Phoenicians).

Hunham greets his class of students with the Latin "salve". This is a greeting for a single person; the plural equivalent is "salvete".

Paul is teaching "The Peloponnesian War" and announces to his pupils: "We've already met Pericles. Now meet Demosthenes". But Demosthenes, the greatest orator after Pericles, was born many years after this book was written. The script confuses the great orator Demosthenes with the (somewhat) minor figure of General Demosthenes, who features in the book.