Summer Love (a.k.a. Beach Story) - S5-E9
Continuity mistake: In the scene at the end where "Babewatch" is being filmed, when Arnold drowns and the lifeguards save him, he is wearing his plaid shorts. A shot later, he is wearing his blue swim shorts. (00:22:34)
Stuck in a Tree / Rhonda Goes Broke - S5-E10
Other mistake: Stuck in a Tree: In Arnold's imagination, when the gang passes the huge tree on the conveyor belt, notice how huge Sid is compared to Rhonda. It looks as if Sid was meant to be in front of Rhonda, but was instead improperly layered behind her. (00:07:43)
Stuck in a Tree / Rhonda Goes Broke - S5-E10
Continuity mistake: Stuck in a Tree: When the fire truck shows up at the end, in Arnold's close-up, his sleeves are drastically shorter than usual. (00:10:29)
Stuck in a Tree / Rhonda Goes Broke - S5-E10
Revealing mistake: Rhonda Goes Broke: When Rhonda says, "I'm power walking. It's the healthiest way to get home," her mouth disappears four times. (00:21:42)
Stuck in a Tree / Rhonda Goes Broke - S5-E10
Other mistake: In the scene after the garbage dumpster scene, Buckley's lips disappear briefly while he's talking.
Beaned / Old Iron Man - S5-E11
Continuity mistake: Beaned: When Arnold is walking Helga to school and she sees some flowers, they are both standing on the sidewalk. Two shots later, they are on the road. Also, when Arnold walks up to Helga, he is in mid-air, and when Helga stands up, she is also in mid-air. (00:05:53)
Beaned / Old Iron Man - S5-E11
Continuity mistake: When Arnold reads to Helga, the book title says "GEO-" and "GRAPHY" (two words); the next day, it says "GEOGRAPHY" (one word).
Arnold Visits Arnie / Chocolate Boy - S5-E12
Audio problem: Arnold Visits Arnie: When Arnold, Arnie, and Lulu leave Arnie's house, the shot fades to them at the swimming hole. Lulu then says, "So," but her mouth does not move. (00:04:39)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: When Arnold and Lulu are in the swimming hole, Lulu tells Arnold to meet her later for a private swim. Then, when Arnold tells her, "But you're Arnie's girlfriend," his hat is missing. (00:05:14)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Audio problem: Arnold Visits Arnie: In the country store, when Lulu tells Arnold to get some of the apple butter on the shelf, Arnold says, "Sure," but his mouth doesn't move. (00:05:41)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: In the country store, when Arnold says, "But, what about Arnie?" and it cuts to Arnie counting the bubble gum, the "1893" on the window is red but changes to white in the next shot. The "Est." also disappears. (00:05:53)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: When Arnold walks out of the movie theatre, he walks into Hilda and they fall over. In the next shot, they turn 90° counterclockwise. (00:06:45)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: At the movie theatre, Lulu is shown sitting in the seat to the right of Arnold. Then, when Hilda goes to sit next to Arnie, Lulu is missing from that seat, then reappears in the next shot. (00:07:47 - 00:08:18)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Audio problem: Arnold Visits Arnie: During the hayride, Arnold tells Hilda that she has a little straw in her hair. When he says, "Let me get it for you," his mouth does not move; it just stays in a smile. (00:09:14)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Other mistake: Arnold Visits Arnie: When Arnold wakes up from his dream and he screams, his collar briefly loses its colour. (00:10:38)
Character mistake: Helga makes Arnold sit in a plate of chocolate pudding as a prank. Arnold then asks Grandpa on the phone to bring him a new pair of pants. When Grandpa arrives, he asks Arnold, "What's that on your pants?" The pudding is not on Arnold's pants; it's on the back of his shirt. (00:06:25)
Other mistake: When we first see Arnold walking Helga home after school, as Arnold says, "I never meant for this to happen," Arnold and Helga are briefly duplicated. As the shot continues, Arnold's backpack duplicates repeatedly. (00:11:22)
Continuity mistake: Helga makes Arnold sit in a plate of chocolate pudding as a prank, leaving a huge chocolate pudding stain on the back of his shirt. Then, when Arnold picks up the gift box from Grandpa and returns to the cafeteria, the chocolate pudding is gone from his shirt but reappears later on when Arnold and Helga are at Slausen's Ice Cream. (00:12:37)
Gerald's Game / Fishing Trip - S5-E15
Continuity mistake: Gerald's Game: When Arnold asks Gerald if he was in the alley near Dr. Steiglitz's office, Gerald is holding three books, with a purple book on top, and a green book on the bottom. Right before he drops them, the two books have switched places, and the purple book changes to blue. (00:03:24)
Gerald's Game / Fishing Trip - S5-E15
Continuity mistake: Gerald's Game: When Arnold asks Gerald if he was in the alley near Dr. Steiglitz's office, there is nothing in the bottom shelf of Gerald's locker. When Gerald puts his book "The King Rules" in his locker, some books appear in the bottom shelf. (00:03:34)
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.