Other mistake: They search for the location of the Village by using map co-ordinates, which are checked out using a military aircraft. The Village is eventually discovered and found to be on an island somewhere in the Mediterranean sea. Number 6 is ejected from the aircraft back to the Village. However, in the final episode, i.e. 'Fall Out,' the Village is found to be in somewhere in the UK. They escape in a truck and end up traveling to London.
The Bullet - S1-E17
Other mistake: After learning Carl Hamlin had been shot with a 9mm bullet instead of a .38 revolver, the detectives, along with Ray Murray from SID, return to the scene where they conclude no one could have shot Hamlin and left the study. Murray asked Friday if they had seen an empty shell casing, to which Friday correctly replies that "there was no reason to look for one." However, they start to look around the study to find one after already realizing that he could not possibly have been shot there.