Great Superbowl, but don't like the no calls at the end

The Niners showed resilience like they had all post season long, coming back from a 22 point deficit.  At the end of the game I really didn't like the no calls.  There were possibly three calls that looked as if they were missed towards the end of the game.  The first one came on the Niners 2 pt conversion attempt where the Ravens appeared to have been offsides before the ball was snapped.  The last 2 came on the final drive in the red zone.  The first no call that I did not like was a short pass and the receiver took a shoulder to the head as soon as he caught the pass, this would be known as "defenseless receiver" in the NFL rulebook.  The last no call that everyone saw was the last play of the game from the 5 yard line.  Defensive backs are allowed to make contact within the first 5 yards of the line of scrimmage, which did occur legally but the receiver did reach the endzone which would have put him past 5 yards and there was still a lot of contact from the DB.  Should have been defensive holding or pass interference and the game shouldnt't have ended.  I know its the Superbowl, but these are rules that are enforced all year long, and in such a big game, how can you not call something that was so blatant?