When Wayne meets Bjergen Kjergen, we see alternating front and back shots of her. From the back, she is leaning to the side and her arms are crossed. From the front, she is leaning forward with her hands folded.
When Wayne pulls in at the gas station, across the way can be seen a building with the lettering "Bonita High School, Home of the Bearcats". Bonita High School is in LaVerne in California, a long way from Illinois where the film is set.
Jerry Segel has a white eye, which he claims is because is because he's a partial ocular albino. He explains that his white eye has no pigment which is the cause of there being no color. This is false. It is scientifically impossible to have a white eye. When a human eye has no pigment, the eye is blue light.
When showing Wayne the vinyl records she got at a garage sale she states: "Can you believe they're not making vinyl anymore?" This isn't true. Vinyl albums have always been, and even in the 21st century still is, the media of choice among audiophiles.
When Wayne is driving away in the sports car after the glass/chicken/melon crash, he drives past a sign that says "Santa Barbara". Santa Barbara is in southern California, many hundreds of miles from Aurora, Illinois, and would not be signposted that far away, showing that the film is being shot in California rather than Illinois.
The scene is a shot-for-shot homage of the ending scene from 'The Graduate' in which Dustin Hoffman takes the Santa Barbara freeway exit in a similar vehicle just before stopping at the same service station.
In the "returning home from England" plane scene, it's obviously a mirror image (identifiable by the writing on the plane being reversed.) However due to the nature of the jokes during the plane scenes, this was probably intentional.