(at around 1h 28 mins) Wong Fei-hung fights for several minutes under heavy rain, however when he gets kicked into his house, his clothes and hair are dry.
(at around 5 mins) When Wong Fei-hung opens the fan at the beginning, in one shot he is opening it with both hands. In the next shot he is opening it with one hand.
(at around 54 mins) A 31-star US flag is seen shortly after an adult Wong Fei Hung attempts to defend the Po Chi Lam clinic from a fiery attack. The 31-star flag was used from July 4, 1851 to July 3, 1858. Wong Fei Hung was born on July 9, 1847, and so could not have been older than a few days shy of his eleventh birthday when this flag was still in use. Also, the rows of stars shown on the 31-star flag are inverted. The flag shown has rows of 7, 6, 6, 5, and 7 stars respectively (from top to bottom). The actual flag has rows of 7, 5, 6, 6, and 7 stars top to bottom.
(at around 39 mins) When Aunt Yee is fitting Fei-hung for a suit, she sees his shadow on the wall. Standing a few inches behind him, she traces his silhouette with her finger, obviously without touching him. However, when she touches his shadow ear, it flickers, meaning she actually touched his real ear.
When Wong Fei-Hung jumps off the tea-house, while kicking the Shaho gang leader, it is quite clearly another actor (Xiong Xin Xin).
During the fight scene at the theater, when Aunt Yee is helping the Jesuit over the railing, the Jesuit's shoes are clearly seen to have a modern tread.
A 50-star US flag can be seen in the Americans' ship.
When Master Yim And Wong Fei-Hung fights on top of the latter's, they hit their feet together. When Master Yim does the back-flip, a wire is clearly seen holding him up.