I spotted a goof at the very end of this episode. The Amelia Sequence is basically the numbers that Jake "finds" in each episode, in order. So, this episodes target number is 1188. Arthur's chalkboard is missing last episode's number, 6, and this episode's number, 1188. Martin goes up to the board and adds "1188" but he either forgot the 6, or doesn't know about it either?
But he was given the Amelia sequence several episodes ago, and he should know that Jake is finding the numbers that Arthur wrote down. It is my opinion that Martin should have known about the 6, but the actor and the crew just goofed.