Mr. Gregory Devry (No. 95) - S3-E11
Other mistake: After arresting the Reddington impostor, Ressler states that while hunting Red they had only one photo with a "passing resemblance to the man we've been working with." In S1E1 you can however see a high quality picture of Red on the front desk screen while he is arrested. (00:32:25)
Suggested correction: The photo that's seen on the front desk screen is the same photo on Reddington's wanted poster, which has been seen a number of times in the show. That is the 1 photo the FBI have that has a "passing resemblance" to Reddington today, which is what Ressler is referring to.