When the Teacher's sixth and final pupil introduces himself to the Lizard, he calls himself "Number 4" when he is actually "Number 6". This is undoubtedly a error in the English dubbing, not in the original Mandarin dialogue.
Near the end of the film when the Lizard, the Scorpion, the Snake, the Centipede and the Teacher's sixth and final pupil confront each other at the Snake's mansion, the Lizard calls the Centipede "Number 5". The Centipede was actually "Number 1" and was referred to as such throughout the rest of the film and the Toad was actually "Number 5" and was also referred to as such throughout the rest of the film. This is undoubtedly an error in the English dubbing, not in the original Mandarin dialogue.