Manual error
 

One error in the obstacle of the moat was that the depth of the moat is 2 inches not 2 feet. 2 feet is statistically impossible so it only makes sense to be 2 inches.

Re: Manual error
 

Read it again. They say that it is 2 1/2 inches high. Depth is referring to a different dimension - specifically, the distance across the moat.

And if in doubt, just look at the pictures...