I am always amused that at the end of Jackie Chan films there is usually a series of short cameos of things that went wrong whilst making the film.
It is delightful that such a famous film star has such a sense of fun and such lack of ego that he can enjoy it even when he is the butt of the joke, or the scene depicts his own failings.
Likewise, the reality in Wendeltrap Tai Chi is that things sometimes do go wrong.
Also we are not machines but really like to have fun.
Here are some snippets which happened when a camera was there:-