Although the movie takes place in the 1930s, in the factory showdown with Ip Man, Jin Shanzhao is shown wearing modern-day jungle boots of the sort worn by today's soldiers, especially visible when Ip Man slams his foot with his long staff.
The first duel between Ip Man and Jin takes place in Ip Man's home. When Jin pulls out his sword, Ip Man reaches for what looks like a feather duster (a bamboo rod with chicken feathers). When their weapons clash, the sound is of metal-on-metal, despite the fact that Ip Man is not fighting with a metal weapon.
At the end of Ip Man's duel with Master Liao, Ip is shown to be flipping Liao to the ground at a position very close to the door. As soon as Liao is on the ground, the next shot shows both fighters having moved several feet away from the door when no such horizontal movement was made.
When Ip Man gives Yuan the box that his dead brother cherished and walks away (towards the camera), near the end of the shot, Yuan is seen to open the box. On the next cut-scene, the box is closed and he is seen to open it again.