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 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: 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: 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.
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: In "Baby Oskar" the apartment number on the door to Oskar and Suzie's apartment appears and disappears multiple times throughout the episode.
Grandpa's Sister / Synchronized Swimming - S4-E12
Continuity mistake: Synchronized Swimming: In the pool scene at the beginning, we see a close-up shot of Connie and Maria. In the next shot, they are nowhere to be found. The three kids surrounding the pool in the beginning also disappear. (This happens because the opening shots are reused from the episode "Sixth Grade Girls.") (00:12:01)
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)
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)
Continuity mistake: When Arnold is sitting in the kitchen with Dino's personal stuff, Grandpa offers him a shrimp cocktail, and Arnold turns his head to look at it. In the next shot, he is suddenly looking inside the box. (00:06:45)
Monkeyman! / Buses, Bikes and Subways - S5-E1
Continuity mistake: Monkeyman!: When Sid tells the kids that Gerald should tell the legend of Monkeyman, Arnold is squinting. In the next shot, he's not. (00:01:41)
Monkeyman! / Buses, Bikes and Subways - S5-E1
Continuity mistake: Buses, Bikes, and Subways: When Mr. Simmons shows the class the huge vat of chocolate, Phoebe points out that somebody is swimming in it. Then in the shot where Chocolate Boy rises up out of the chocolate, behind the vat, there is another vat which wasn't there before. (00:13:48)
Monkeyman! / Buses, Bikes and Subways - S5-E1
Continuity mistake: Buses, Bikes, and Subways: Helga wears a watch on her right arm throughout the episode. However, when Helga approaches Sheena's uncle Earl and wakes him up, her watch is missing, then reappears when Earl's boat sinks. It disappears again when Helga comes up from the water, then reappears a moment later. (00:18:59)
Monkeyman! / Buses, Bikes and Subways - S5-E1
Continuity mistake: Buses, Bikes, and Subways: After Helga and Harold first encounter Earl, it cuts back to the class on the bus. Phoebe is not sitting in the seat behind Arnold and Gerald, but in the next shot, she suddenly appears. (00:19:10)
Monkeyman! / Buses, Bikes and Subways - S5-E1
Continuity mistake: Mr. Simmons counts 30 students in the bus, but nowhere near that many got off (nor have nearly that many fourth graders ever been shown).
Helga's Masquerade / Mr. Green Runs - S5-E2
Continuity mistake: Helga's Masquerade: When Arnold compliments Lila's bows, she says, "In fact, I'm certain I wear them just, every old day." Ironically, her right bow disappears mid-shot, and it remains missing in the following shot. It comes back shortly after. (00:01:50)
Helga's Masquerade / Mr. Green Runs - S5-E2
Continuity mistake: Helga's Masquerade: When Helga and Lila are at Slausen's Ice Cream, after Helga asks Lila where she gets her material from, Lila's right arm is below the table, but a shot later, it's above the table, and a spoon appears in her hand. (00:03:18)
Helga's Masquerade / Mr. Green Runs - S5-E2
Continuity mistake: Helga's Masquerade: When Helga and Lila are at Slausen's Ice Cream, after Helga asks Lila how she can learn to act so nice to people, she grabs her milkshake with her left hand. A shot later, she is now holding it with her right hand, and a spoon appears in her left hand. (00:03:30)
Parents Day - S5-E6
Continuity mistake: During the flashback, when little Arnold says goodbye to his parents, in the next shot of Stella and Miles, the bag's strap is slung over his dad's left shoulder as a crossbody, but mid-shot, the strap switches to his right shoulder with the bag on the opposite side. (00:14:30)
Parents Day - S5-E6
Continuity mistake: During the triathlon, Miriam and Grandma climb up the ropes of the brick wall, but when they both get to the top, the ropes have vanished. (00:20:36)
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.