Snack Time - S1-E1
Revealing mistake: When Steve skidoos back to the thinking chair, the tree branch is cut off.
Snack Time - S1-E1
Revealing mistake: When Steve skidoos to the farm, there is a white border around the screen.
A Snowy Day - S1-E10
Revealing mistake: During the mailtime segment, when Mailbox shakes snow onto the chair, a small part of him is cut off, and you can see the letter being held behind him. This also happens when Mailbox opens his door, and you can even see a crew member's hand move away as Steve grabs the letter. (00:17:38)
Revealing mistake: The first clue, the boots, are cut off to the left.
Blue Wants to Play a Song Game - S1-E14
Revealing mistake: After Blue and Steve play the monkeys jumping on the bed game with the sock monkey, when the mail time song plays Steve gets up excitedly and his arm and hand get cut off.
What Story Does Blue Want to Play? - S1-E16
Revealing mistake: When Blue wants to play Blue's Clues, the paw print is off-model.