When Sue Ellen asks Kenny to turn the music down, she says "When are you going to start helping me, you lazy little punk?", but mouths the word "prick". Director Stephen Herek wanted to avoid any chance of the movie getting an R rating, so he had the line dubbed.
At the beginning of the movie, Kenny arrives home with a marijuana plant in a bag, which he puts on his window. The pot is clearly plastic. The plant falls down and makes the sound of a ceramic pot breaking.
Sue Ellen comes home from work and puts her purse on the kitchen island. In the next scene at the office, the secretary goes through Sue Ellen's things, finds her driver's license in her purse, and discovers that Sue Ellen is 17.
The film is set in summer 1990, but the Q.E.D. report on Sue Ellen's computer screen lists March 22,1989, as the date. The posters in the Clown Dog advertise a circus on Friday April 20th. In 1989, April 20th was not on a Friday.
When Kenny goes to the window after Walter falls from the roof, he clearly has two rips in the seat of his jeans, just below the pockets. Later, at the hospital, he only has one rip in his jeans, much lower on the left leg.
When Sue Ellen and Bryan talk after he gives her and the kids a ride home, Kenny yells that Zach and Melissa are fighting over the last snowball. He says it's the last food in the house. The next morning, Swell pours a huge bowl of Cap'n Crunch for the kids to share.
When Sue Ellen arrives at the hospital after Walter breaks his leg, he has already been treated. When she arrives she tells them that she is his mother, and never does any paperwork. Outside of life-threatening situations, minors can not get health care without parental permission.
Sue Ellen's alarm clock goes off at 5:30am. When the scene goes wide, there is broad daylight with no sign of "morning pink" coming through the windows. Bright sun rays on various items in the bedroom indicate that the sun is considerably above the horizon. In Los Angeles, the sun never rises earlier than 5:40 am.At most, the sun would be just breaking the horizon.
When Brian and Sue Ellen are sitting on the beach waiting for the grunion run, Brian says that grunion fish males and females do not mate at the same time. In reality, the female grunion buries her eggs and waits for the male to wrap around her and release his sperm before abandoning the eggs.
Numerous characters refer to Sue Ellen as a 17-year-old. The film is set during a 1990 Los Angeles school summer, and the birth date printed on her driver's license is December 19, 1973, so Sue Ellen is actually 16.
When Sue Ellen is on her bed talking to Nicole on the phone, she colors purple stripes on a shirt in a fashion ad. When the kids come in to complain about the babysitter, the stripes are not yet colored in.