My biggest pet peeve with replay standards in pro sports. Especially in the NFL, I think referees too often are reluctant to call what they think they see on the field, knowing that they have replay to fall back on. The issue is, by NOT calling what they believe they see, they've established a presumption that their call is correct, which presumption is difficult to overcome. Then you have the nonsense of getting a certain number of challenges ...if I challenge a call on the field/court, and my challenge is correct, why should that be held against me/my team?