Rumble in the Big House - S2-E9
Factual error: During the final confrontation, Xiao Fung keeps blowing and blowing, and Valmont/Shendu, Finn and Ratso are blown through the tunnel and right into the middle of a garbage dump. But they have to break through a layer of garbage in the process, and since Xiao Fung's breath keeps blowing, there should have been a hole through which his windy breath would pass, instead of an intact layer of refuse.
Factual error: When Jackie and Hak Foo slug it out in empty space, their punches and kicks should keep them helplessly spinning around, since there is neither gravity nor air resistance to break the momentum of their movements.
Factual error: When Jackie releases the lotus flower from his helmet, he starts holding his breath - an unwise move to do in reality. With the pressure in his suit dwindling rapidly and no outside pressure in vacuum to counter the air pressure in his lungs from holding his breath, he would suffer from rapid decompression. While Jackie would not explode, it would cause a most certainly fatal lung trauma.
The Chan Who Knew Too Much - S2-E34
Factual error: Jackie and Jade flee from the Magisters down a sewer manhole, starting in Wiltshire County (where the real Stonehenge is located) and ending at the bridge right next to London's House of Parliament - which lie apart by about 90 miles of linear distance. The British sure have one VERY extensive linked sewer system.