Character mistake: When talking about Mike and Ike giving them descriptions while on NZT, he mentions that he once heard Ike's name but forgot it. Completely impossible since his memory is impeccable on NZT.
Stop Me Before I Hug Again - S1-E13
Character mistake: In Brian's "Laws I Have Broken Since Joining FBI" list, item #30 misspells the word "recorded" - "30) Recoreded NFL Game Without Consent." He'd only have that knowledge if he was using NZT, and if he was, he wouldn't make a mistake like that.