New Bully on the Block / Phoebe Breaks a Leg - S5-E5
Other mistake: Phoebe Breaks a Leg: When Phoebe is about to be taken to the hospital, as Gerald says, "Now that is truly sad," there is an animation error where Arnold's mouth opens and closes for a split second. (00:14:42)

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)

Parents Day - S5-E6
Continuity mistake: When Miriam and Grandma are climbing up the ropes of the brick wall, there is no one standing on the balance beam above the gelatin, but when they ride the zip lines, Bob and Grandpa are suddenly standing on it. (00:20:42)
Parents Day - S5-E6
Other mistake: After Grandpa knocks Bob into the gelatin, Arnold and Grandma run up to Grandpa. In the next shot, Arnold's left side hair has five spikes instead of four like it should. (00:21:55)

Parents Day - S5-E6
Continuity mistake: In the scene where Arnold's parents leave for the last time, Grandma's hair is dark at first, then it becomes purplish-gray.

Parents Day - S5-E6
Continuity mistake: When Grandpa enters and exits Arnold's bedroom, the door opens the opposite way in various shots, with the doorknob on either the left or right. Additionally, the light switch beside the door appears and disappears, between shots.

Parents Day - S5-E6
Continuity mistake: In the tricycle section of the last event, the chinpiece of Helga's helmet keeps switching colors.
Helga's Locket / Sid and Germs - S5-E7
Other mistake: Helga's Locket: When Helga first sneaks into the boarding house, Grandpa is shown trying to open the locket. When the camera pans over to Helga and stops, a small part of Grandpa is still visible; then he disappears mid-shot. (00:03:25)

Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: When Arnold is cutting a photo of Grandma in his room, there is nothing on his computer screen. Then, when Arnold starts to leave his room, a photo of Lila appears on the screen. (00:05:48)

Helga's Locket / Sid and Germs - S5-E7
Other mistake: Helga's Locket: When Helga climbs to the top of the boarding house and looks at Arnold and Grandpa through the window, as Arnold tells Grandpa, "It's embarrassing and weird," Helga's left sleeve is incorrectly coloured pink instead of white. (00:09:02)
Helga's Locket / Sid and Germs - S5-E7
Plot hole: Helga's Locket: When Grandpa tells Arnold about his grandfather's Shiska-Bob Stick, he says that no one has ever touched it since his grandfather's last barbecue on July 16, 1926. However, in the season 3 episode "Grandpa's Birthday," Grandpa says that his grandfather died in 1921 while he looks at the photo album. (00:09:55)
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: When Arnold and Grandpa are in the basement trying to pry open the locket, the tools on the workbench constantly rearrange themselves in various shots. (00:10:06)

Helga's Locket / Sid and Germs - S5-E7
Other mistake: Helga's Locket: When Arnold and Grandpa are in the basement and Arnold says that they need the Shiska-Bob Stick, a small portion of the brown paper bag on the workbench is missing. (00:10:06)

Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: After Helga leaves the boarding house through the basement window at the end, when it shows a close-up shot of the locket in her hands, Helga's sleeves are way longer than they should be. (00:11:37)
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: When Abner takes the locket from Helga at the end, Helga chases after him. In the next shot, they are shown running past the basement window of the boarding house, but that's impossible because they started running away from the basement window in the previous shot. (00:11:42)
Helga's Locket / Sid and Germs - S5-E7
Audio problem: Helga's Locket: When Abner takes the locket from Helga at the end, Helga screams, "Come back here, you filthy pig!" but her mouth hardly moves. (00:11:42)

Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: When Sid decides to be a slob again, he picks up his frog and you can see that he has gloves on. When the following shot shows a close-up of the frog in Sid's hand, the hand holding the frog does not have gloves on.

Summer Love (a.k.a. Beach Story) - S5-E9
Continuity mistake: When the seagulls start flying above Arnold and Summer, they are both holding hands. In the next shot, they're not. (00:11:26)
Summer Love (a.k.a. Beach Story) - S5-E9
Continuity mistake: When Helga sprinkles bread crumbs around Arnold and Summer, six seagulls come and fly above them. In the next shot, the shadows of the seagulls are visible, but there are only two seagull shadows. Then when both look up at them, there are only five seagulls flying above them instead of six. (00:11:26)







Answer: No, he did not. He is seen getting off the bus with a suitcase, so he must have not been home for a few days so there is no way he could have known.
Bowling255 ★