When Arnold is walking to the stairs while the crowd is laughing at Lockjaw, Eugene is nowhere to be seen.
When Lockjaw is forming from Arnold's floor, a section fills in yellow for a few frames.
When Eugene is talking on the bus, he is wearing a red sweater with a white collar but in the other scenes he is seen with his normal shirt on.
The radio incorrectly calls Lockjaw a Galapagos Tortoise even though he is a sea turtle.
He is also shown to be walking underwater which is impossible for sea turtles or even tortoises to do, and if they did this then the animal will die.
The jellyfish in the aquarium can be with octopus-like tentacles even though jellyfish are not cephalopods.
Lockjaw is shown to be about as big as a Leatherback Sea turtle even though Lockjaw appears to be a green sea turtle, which are smaller.
When Arnold arrives home after the field trip, Helga's shirt is pink, and her bow and jumper are red.
When Arnold was talking to his grandma about LockJaw, his door is open, but then when Grandma says, "Well this is an outrage!" The door is closed and also, she seems to have two eye puples in one eye each facing different directions.
