Continuity mistake: When Audrey eats her gelato on the steps of the Spanish Plaza, if you look closely, the time is about 12:00 when she buys the cone. However, when she starts eating it, you can see that it's past 3:00.
Continuity mistake: When Audrey and Gregory are saying goodbye in the car, there are two shots where rain is visible outside the car window behind them. When Audrey gets out and walks away, however, it's dry outside.
Continuity mistake: During the scene where Gregory Peck pretends to bump into Audrey Hepburn on the Spanish Steps we see several shots of a clock in the background showing the time is around 4.55pm. When he sits down the clock is around 11:30. Then the very last time we see it, the time is 3.50pm.
Continuity mistake: When Ana, Joe and Irving meet at Rocca's, Joe pushes Irving over and a drink spills on his shirt. When he is on the ground, the shirt has a large spot on it, when he stands up, the spot is dry.