Hall Monitor / Harold's Bar Mitzvah - S2-E15
Continuity mistake: Hall Monitor: In the cafeteria, when Gerald throws his detention slips on the floor, Phoebe gives him another slip. Phoebe is first behind the railing, but in the next shot, she is in front of the railing. In the following shot, she is behind the railing again. (00:08:26)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: When Helga chooses Phoebe to be the new hall monitor, as Phoebe is walking to the stage, Iggy's hair is incorrectly coloured black instead of brown. (00:02:30)
Runaway Float / Partners - S2-E20
Continuity mistake: Runaway Float: The big beeper float constantly changes appearance during the parade. Some examples: The sign saying "Let's Go Downtown" on the front changes to "Let' Go Downtown" in one shot. The sign saying "Let's Go Downtown" on the back is missing in one shot. The orange base is sometimes blue. The blue city design around the base sometimes isn't there, and it even changes colour. (00:08:17)
Runaway Float / Partners - S2-E20
Other mistake: Runaway Float: When Bob asks the kids who wants to ride on the float, Arnold says to them it's great the way it is. In one shot, Iggy's hair is incorrectly coloured black instead of brown. (00:05:52)
Runaway Float / Partners - S2-E20
Continuity mistake: Runaway Float: When Arnold reaches the parade float on the bike, Iggy's shirt is incorrectly coloured green instead of purple. It's also green when the float rides past Mayor Dixie. (00:09:45)
Continuity mistake: Ms. Perfect: When Lila and her father are eating dinner, Lila's spoon is in her can of beans in one shot. When the angle changes and her father says, "You sure are quiet tonight," her spoon disappears from the can of beans, then reappears in the next shot. (00:19:05)
Other mistake: Ms. Perfect: When Mr. Simmons tells the class, "I have a note from Lila's father," his right sleeve briefly turns green. (00:19:22)
Save The Tree / New Teacher - S2-E1
Audio problem: Save the Tree: At the end, when Bob says, "Yeah, I'll just build my beeper emporium in that vacant lot down on Vine Street," his mouth doesn't move until the word "build." Arnold's mouth also doesn't move when he says, "Huh?" (00:11:27)
Other mistake: Ms. Perfect: When the girls sabotage Lila's lunch, as Helga pours out Lila's milk from her thermos, the milk crosses an invisible line and disappears. (00:16:56)
Continuity mistake: Ms. Perfect: When Lila goes to Patty's locker, the books she is holding constantly change. First, she is holding two books, then three, then the red book is suddenly on top, then the red book disappears and the rectangle on the brown book changes to white, then it goes back to yellow and the blue book gets replaced by the red one, and finally, the blue book reappears (she is also suddenly not holding the locker handle, and the way she holds the books changes). (00:15:48)
Continuity mistake: Ms. Perfect: When Patty opens her locker and the jello falls on her, her head is raised above the floor, and there is no jello on her head. In the next shot, her head is on the floor, and there is jello on her head. (00:16:24)
Audio problem: Ms. Perfect: When Lila says, "Whatever you do, don't smell that cow," the boys are heard laughing, but only Stinky is shown laughing. (00:15:14)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: In the credits, actor Elliott Gould's name is misspelled as "Elliot Gould." (00:22:59)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: In the credits, Justin Shenkarow is credited twice for voicing Harold. (00:22:59)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Continuity mistake: Harold's Bar Mitzvah: In the beginning, when Stinky asks Harold if he wants to play stickball, there is no wristband on his arm. Harold says he has to go do his lessons, and in the next shot, a wristband appears on Stinky's arm, then disappears. Later on, when Harold comes out of the synagogue, his wristbands are back on his arms. (00:12:03)
Tour de Pond / Teachers Strike - S2-E18
Continuity mistake: Tour de Pond: When Rex's grandfather walks up to Arnold's Grandpa at the end, his badge has eight squares on it, but in the next shot, it changes to four stripes. (00:11:20)
Tour de Pond / Teachers Strike - S2-E18
Continuity mistake: Tour de Pond: When Rex notices that Arnold's boat is winning and starts running, the red and yellow squares on his grandfather's badge change to red and black. (00:10:18)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Arnold, Gerald, and Grandpa are first shown at the Tour de Pond race, their ship is not sitting on the sidewalk, but rather on the edge of it, which makes it look like it’s floating in mid-air. (00:05:02)
Tour de Pond / Teachers Strike - S2-E18
Continuity mistake: Tour de Pond: When Gerald puts the boat made out of the block of wood in the fish tank, the sail is pointing towards the right, but when the boat sinks, it's pointing towards the left. (00:02:18)
Tour de Pond / Teachers Strike - S2-E18
Continuity mistake: Tour de Pond: When Arnold makes a boat out of a block of wood, there is a blue cup on the newspapers with gray scissors and another orange object in it. In the next shot, the cup becomes green, and the scissors and other object become pink. As the scene continues, they change colours a few more times. The pencils also become the same colour as the newspapers. (00:02:11 - 00:03:49)
Answer: The show is based in present day times. Plus most cars aren't old fashtioned, I recall seeing a limo and not to mention a cherry picker, etc.