When Leopoldo and his wife are walking the street near a street coffee vendor, the extras in the background pass several times.
When Giancarlo gets into the shower on stage, he gives his towel to a stage hand. When he gets out after his aria, the towel is around his waist. There is a brief moment when the camera is on the audience and not on him, but hardly enough for the stage hand to come on stage, hand over the towel and disappear off stage again.
When Leopoldo leaves his house to go to work, he walks to his car and the front wheels are pointing to the right. He leaves the car there. When he comes home, the car's wheels are turned to the left.
When Leopoldo exits his home for going his work, he walks to his car and front wheels are looking to right side. But he can't get in his car and driven by another car with his driver. After came to his street for entering his home, you can see that his car's wheels are turned to left side.
When Antonio is calling Milly, the call tone is the American call tone. In Italy, when you're calling someone you hear a different call tone. (Not to be confused with the ring tone).
When Leopoldo arrives at his house as he is being pursued by the media, he fumbles to get his key into the lock of his front door unsuccessfully. The door opens anyway and he enters his home.
Roberto Benigni is described at the beginning as a "typical middle class Roman" but throughout the movie he acts with his notorious Florence accent - much different from a Roman's.
Antonio and Milly are supposedly from Pordenone, Nothern Italy, but they speak with a thick Roman accent.