Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: In "Baby Oskar" when Suzie answers the phone there are 12 buttons on the phone, but when she is sitting on the bed there are 9 buttons.
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Lila was pretty much entirely underwater in a "standing" position when Arnold rescued her, how come suddenly the water only reached her knees?
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: When the sign for the Built-To-Hurl is first shown, it is spelled with a hyphen between "To" and "Hurl." When the sign is shown again, that hyphen is missing, then reappears a moment later. (00:07:19)
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: At the end, Arnold says to Lila that he will walk her home. In the next shot, a janitor suddenly appears behind them. (00:11:40)
Full Moon / Student Teacher - S4-E1
Continuity mistake: Full Moon: Throughout the episode, Harold's eyes change from yellow to white during a few consecutive shots, as well as mid-shot.
Full Moon / Student Teacher - S4-E1
Continuity mistake: Full Moon: When Arnold leaves the school at the beginning, he is carrying a green book. A few seconds later, the rectangle on the cover changes to white, then back to green. (00:03:14)
Full Moon / Student Teacher - S4-E1
Continuity mistake: Full Moon: When Principal Wartz tells Arnold to see him every day after school for the next four weeks, the words on his office door are yellow. About a second later, they change to red, then back to yellow. (00:02:57)
Back to School / Egg Story - S4-E8
Continuity mistake: Egg Story: When Arnold shows the little chick to the class, Phoebe is sitting behind Harold, but she is suddenly standing in the next shot. (00:22:30)
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: Weird Cousin: When Lila tells Arnold, "Going to a movie together sounds kind of like a date," the way she holds her book changes between shots. (00:01:41)
Grandpa's Sister / Synchronized Swimming - S4-E12
Continuity mistake: Synchronized Swimming: During the swimming tournament, the boys take off their jackets beside the pool. When the boys jump in the pool, they disappear. (00:20:55)
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: When Arnold asks the man at the CheeseBall Toss for three tries, Eugene in the background has black skin and a red shirt, like Gerald. His shirt is also red in a later shot when Arnold is trying to knock the bottles down. (00:05:52)
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: When Helga drills the hole into the back of Arnold and Lila's boat, she drills it into the side of it, but when it's shown from inside the boat, it's in the center. (00:09:06)
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: Helga drills a hole in the back of Arnold and Lila's boat, but in all the following shots where the back of the boat is shown, the hole is not visible. (00:09:07 - 00:10:31)
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: When Arnold and Lila's boat is stuck at the edge of the waterfall, Lila says, "Arnold, what will we do?", and when the shot changes, Arnold and Lila's hands both move to a different part of the boat. Lila's braids also go from being in front of her shoulders to behind them. (00:10:15)
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: Baby Oskar: In the shot where Suzie tells Oskar, "As long as the baby is here, he's going to have to come first," the stove is drastically further away from the door than usual. (00:13:21)
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: Baby Oskar: When Oskar asks Suzie to make him breakfast, there are two baby food containers on the table. Later on, when Suzie is on the phone and Oskar walks back into the kitchen, the containers are gone. (00:16:14)
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: Baby Oskar: When Suzie says to Oskar, "Tomorrow, tomorrow, tomorrow. That's all I ever hear from you," she sets the baby bottle on the table. In the following shots, the bottle is nowhere to be found on the table. (00:15:23 - 00:15:57)
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: Baby Oskar: In the beginning of the episode, Suzie is ironing Oskar's pants, and the laundry basket is on the floor beside her. Suzie picks up his pants and lays them out on the ironing board, and in the next shot, the laundry basket is suddenly in her hands, and the pants are in the basket. (00:12:21)
Grandpa's Sister / Synchronized Swimming - S4-E12
Continuity mistake: Synchronized Swimming: When the boys take off their jackets during the swimming tournament, Gerald's boots change from brown to black mid-shot, and when the camera pans over to Stinky, his boots are also black instead of brown. (00:20:45)
Grandpa's Sister / Synchronized Swimming - S4-E12
Continuity mistake: Synchronized Swimming: When the boys take off their jackets during the swimming tournament, Sid is missing from the group. When the boys dive into the pool, he returns. (00:20:46)
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.