When Neidermeyer closes the door on Flounder at Omega House, two women in red dresses can be seen coming down a stairway in the background. A moment later, they cut back to an empty stairway, and then the same two girls reappear at the top.
When Katy is walking through the kitchen with her bare behind showing, she passes a refrigerator with a US Bicentennial sticker on the door. The Bicentennial was in 1976, of course, fourteen years later.
In the homecoming parade there is a float showing President Kennedy and the word "Camelot". The use of this word dates from an interview Jackie Kennedy gave Theodore H. White days after Kennedy's assassination in which she revealed that the President listened to the music from the Broadway musical "Camelot" before he went to sleep. The movie occurs before his death and uses a word not associated with the president at that time.
A major song that is featured in the movie is 'Louie, Louie'. The movie is supposed to take place in the Fall 1962 - Spring 1963 timeframe, however, 'Louie, Louie' (by the Kingsmen) was not released until late 1963 (November-December timeframe).
In the check-out line at the Food King, there is an older, electro-mechanical cash register behind Clorette, but from a different angle looking towards Larry, a more modern electronic register as used in the late 1970s is clearly visible in the next aisle over.
In the Food King scene where Flounder is catching groceries tossed by Otter, items on the shelf have UPC symbols, which were not used until 1973. Also, there is Low-Calorie Nestea on the shelf (not available in 1962), and the product prices are too high for 1962.
When the Lincoln is driving away from the Dexter Lake Club, the license plates are blue and gold California plates - similar to Otter's Vette plates that came out in 1970.
-- Oregon plates from this era were very similar to the CA "Blue & Gold" plates. Since this movie was filmed in Oregon, possibly local cars were used.
When Stratton pulls into the motel parking lot, there is a pale yellow Plymouth Volare or Dodge Aspen station wagon parked in the lot. Chrysler didn't introduce the Aspen/Volare until 1975. Furthermore, when he opens the motel room door, a Ford Pinto/Mercury Bobcat station wagon can be seen behind him, which was not introduced until 1972.
When Otis Day and The Knights are performing at the Delta House, the guitar player is seen playing a Gibson Les Paul Deluxe guitar model, which Gibson didn't introduce until 1969 and blues guitarist Robert Cray, who played bass in the band, is seen playing a Fender Precision Bass with (if you look closely) a transition logo, which Fender didn't start using until 1964 and oval-head tuners, which Fender didn't start using on their basses until 1966.
To compound the previously cited geographical error of showing Pac 10 banners in the football stadium (the University of Oregon's Autzen Stadium), there is also an anachronism in this banner display. The Pac 10 was known as the Big 6 in 1962 when this story is supposed to take place. However, an OSU banner can clearly be seen: the University of Oregon and Oregon State University did not join the Big 6 (which then became the Pac 8) until 1964.
The Ludwig logos displayed on the marching band bass drum in the parade was not introduced until the 1970s. The logos used in the 1960s were much smaller, and used a script lettering (as used on Ringo Starr's trap set in the early Beatles films and recorded appearances).
Stratton's Vette have what appear to be blue California plates.
California did not introduce blue plates till 1970. (Best view is when they enter the first party.)
--Oregon plates from this era were very similar to the CA "Blue & Gold" plates. Since this movie was filmed in Oregon, possibly local cars were used.
In the fraternity's basement bar, on the wall in the background is a Coca-Cola sign with the slogan, "Things Go Better With Coke." Coca-Cola didn't introduce that advertising slogan until 1963, a full year after the movie's setting. This is according to Coke's own web site, on a page titled "A History of Coca-Cola Advertising Slogans."
Durng the Toga party, when Otter (Tim Matheson) takes Mrs. Wormer (Vera Bloom) to his room to seduce her, she kicks off her shoes, one after another. The first one lands on the floor, and the other one bounces off the edge of the glass coffee table, then onto the floor, and the sound of shattering glass is heard, yet the table remains intact.
As already mentioned, despite the Mayor's promise of the use of "his free Oldsmobiles," all of the convertibles shown in the parade are 1960-62 Buicks and one Cadillac. The only Oldsmobile in the entire film is the yellow 1963 Dynamic 88 shown in the dealership being hit by the out of control "hand float."
The American flags in Delta/Animal House are all 48-star, World War II-era flags. By 1962, when the film is set, America had 50 states. Therefore, the flags should all have 50 stars (although this could be deliberate to show that the members of Delta House are too lazy to get updated flags.)
When the Omegas are shown waiting for Otter in the Rainbow Motel Chip Diller (Kevin Bacon) is wearing a Faber letterman's sweater with two rings on the sleeve, which would indicate he was a Junior. It is clearly established that in 1962 he is still a Freshman which should have no rings on the sleeve, assuming he could have even earned a letter during his first semester.
In the ROTC scene, after Otter hit's Niedermeyer's horse with a golf ball, the horse rears on its hind legs. When Otter hits his next ball at Niedermeyer's helmet, the horse is shown in a long view perfectly still.
When Bluto is sneaking up on the sorority sisters' house, the exterior shot of the upper floor windows shows the women's actions in silhouette, as if there were a blind or curtains completely obscuring the window. But once Bluto climbs the ladder, each view of Bluto shot from the inside the house shows him through an unobstructed window. Then when the shot switches to a view from the outside, the windows are again obscured.
On the stairs just before the frat hearing, after Boon and Katy finish talking, Otter puts his left hand on Boon's left shoulder. But in the next shot, Otter's right hand is on Boon's right shoulder, and they continue down the stairs.
The rifles carried by the ROTC drill team in the parade are WWII-era M-1 Garands. Yet a few frames after Neidermeyer grabs one of these rifles he is seen loading a WWI-era M1917 Lee-Enfield. This switch was likely done because the clip-fed M1 cannot be manually loaded like Neidermeyer is doing without the use of a special device not in ordinary issue.
After Katie asks Boon about the previous night's Toga party, and she tells him she's busy that night, Otter puts his left hand on Boon's left shoulder. In the next shot, his right arm's on Boon's right shoulder.
When Boon and Otter are looking down on the ROTC group on the field, Boon removes the golf bag from his shoulder, selects a club, and hands the bag to Otter. Following a quick cutaway shot to the field, the very next shot of Boon shows the bag back on his shoulder.
When Pinto is in bed with the girl, she passes out as she is taking her bra off. As she falls over, the toilet paper in her bra hangs over Pinto's hands. The next shot when you see Pinto, the paper is in a ball.
When Katy is about to hand the beer to Pinto, she is holding it in her left hand at the tap. She then switches it to her right hand as Pinto approaches and asks him if he wants a beer as she looks at his name tag she switches the beer back to her left hand. As she says Larry, the camera angle switches from behind her left shoulder, but she is handing him the beer with her right hand.
When the mayor and Dean Wormer are discussing the costs of the parade, the mayor mentions use of his three Oldsmobiles, but the white convertible that the mayor and Dean Wormer ride up in is a Buick, a 1961 LeSabre or Electra. The second red convertible in the parade is a Cadillac. The first red convertible in the parade might be a 1961 or 1962 Olds Cutlass, but looks more like a 1962 Buick Skylark.
When the "Eat Me" car hits the "Togetherness" float and separates the two hands, the white hand moves slowly backward. In the next shot it is rolling forward at full speed when it smashes into the car dealership window.
In the cafeteria scene when Bluto does his "I'm a zit" gag, a side angle shows him holding a scoop of potatoes with his right hand, followed immediately by a front angle of him putting the potatoes in his mouth with his left hand.
As Otter and Boon are admiring Flounder's brother's borrowed Lincoln, there are two guys visible in a wide shot on the roof of Delta House outside a second-floor window. Then, from a closer angle, the two guys have disappeared, but magically reappear when they cut back to the wide angle shot as the Lincoln pulls away.
When the Delta's take their "road trip" and pick up some co-eds from an area girls college, they go to a bar where Otis Day is playing. While sitting inside at the table, the broach Otter's date is wearing clearly moves from the left to right side of her sweater in sequential shots.
When Bluto is in the cafeteria line, he loads up his tray with food. When he moves to the next food station, the tray is reversed. Then half way down the hamburger line, the tray turns back around. Also, different food items are on again and off again.
When Larry and Kent first approach the Delta House, a mannequin flies out of the window and lands at their feet. As they step over the mannequin, a second camera angle shows the mannequin's legs pointing in the opposite direction.
When Niedermeyer is off of his horse belittling Flounder, Otter misses his long golf shot aimed at the horse (NOTE: shot briefly shows Niedermeyer STILL ON HIS HORSE, when he's actually on the ground belittling Flounder.
Blutarsky (Belushi), dressed in pirates garb, climbs up the side of the building before he grabs the banner and rides it across the street. He is chased to the building by ROTC cadets. You can see a civilian give Belushi a two handed lift up in order to help him up the building. The ROTC cadets act as a screen to minimize our being able to see the boost.
The movie is supposed to take place in New England, however during the night time scene in the football stadium with Pinto and Clorette, PAC 10 school banners can be seen hanging on the wall in the background (since the movie was actually filmed at the University of Oregon).
During the parade scene, when a police car skids to a stop on a side street, in the background you can clearly see a sign on a building, "Cottage Grove Sentinel". That's the name of the newspaper in Cottage Grove, Oregon, where the scene was filmed.
When Larry and Kent are accepted to Delta House, they are awoken from bed with carbon dioxide extinguishers. The type used are aluminum cylinders which were not manufactured in 1962 and the label suggests they are Amerex extinguishers, Amerex was founded in 1971.
During the disciplinary hearing scene, there are two flags pictured. One is an American flag, and the other is a Tennessee state flag, even though the film was supposed to have taken place in Pennsylvania. (This was due to the producers not being able to find a Pennsylvania flag that was large enough, so they settled on what they felt to be a fairly generic-looking state flag.)
At the ROTC inspection, Neidermeyer salutes Chip Diller and Diller returns the salute. Since Chip Diller is the lower ranking officer, he should have saluted Neidermeyer, and Neidermeyer should have returned the salute.
The M1917 Neidermeyer shoots at Flounder fires a powerful .30-06 round that should have passed on through the Seltzer bottle and then struck either Flounder or one of the bystanders running in the background.
During the homecoming parade, Stork pushes the Drum Major aside and leads the band into an alley. The band follows him and marches into a wall at the end of the alley. At the very end of the film they are still marching into the wall. In reality, marching band members aren't that stupid.
Army (including ROTC) drill teams are issued non-firing, usually obsolete, rifles for public demonstrations. (In part for safety and in part because of the risk of damage to the weapon.) The rifles used in the parade should not have had firing pins and, therefore, Neidermeyer should not have been able to fire live rounds with them.
During the probation hearing the words "Pan Hellenic Disciplinary Council" can be seen written on the chalkboard; Pan Hellenic Council is the organization that governs sororities, not fraternities, which are regulated by Inter Fraternity Council.
In the food fight scene, all of the ROTC soldiers and Greg Marmalard fall on Neidermeyer when they are chasing Bluto. You clearly see Marmalard get up off of him and continue the chase. But, the next scene, you see the soldiers and Marmalard just getting up off of Neidermeyer.
In addition to the previously mentioned error involving the Mayor's Oldsmobiles, although Mayor DePasto owns an Oldsmobile dealership, the car seen in his driveway when Larry brings his daughter home in the shopping cart after the toga party is a Buick. The mayor also promised free Oldsmobiles for the parade but the decorated car that Bluto tosses Mandy into is also a Buick.
During the riot toward the end when Flounder sneaks up on Neidermeyer to spray him with the bottle of seltzer, Neidermeyer shoots the bottle out of Flounder's hand. There are people running behind Flounder at the time, directly in the path of the bullet, but no one is wounded.
During the toga party, as Boone is sitting alone and singing along with the band, in the background we see what is obviously a Budweiser logo on a lighted sign on the wall. But for the sake of not identifying the product, a large piece of what looks to be black electrical tape is placed over the name itself, leaving the actual logo intact.
In the Food King, Otter picks up a bottle of Mazola to hand to Flounder. Behind it Nestea instant tea mix can be seen, as well as to the right side of it. When looking behind Flounder, it can be clearly seen they are in the coffee and tea aisle. The 6 bottles of Mazola oil are the only bottles on that aisle.