The weirdest thing is when he sits up and roundhouses the funeral director.
No, the most unnerving aspect isn't the shot of Lee's real corpse, or the two other Chinese actors they hired to fill in for Lee in the hopes that Western audiences would be too racist to notice the difference. It's this:
In the movie, Bruce Lee is playing an actor shooting a movie. There is a scene where a stunt goes wrong when a prop gun turns out to be loaded with a real bullet, shooting Lee's character.
What's so disturbing about that? Flash forward to 1993, when Bruce Lee's son, Brandon, was shooting The Crow. During a take when another actor is supposed to fire a gun at Brandon Lee, a bullet fragment that was jammed in the barrel dislodged and caught Brandon right in the gut. In other words, Brandon Lee died under exactly the same circumstances as Bruce Lee's character in the movie.
And not in a vat of toxic chemicals, as his face seems to suggest.
Now, there aren't many movies that feature a character getting shot on a film set by a prop gun loaded with real bullets, so the fact that Brandon Lee's father essentially played out his son's death 20 years before it happened, while working on the movie where he would die himself, is a coincidence so uncanny it that strays into "impossible" territory.
Conspiracy theorists have speculated on every aspect of this bizarre scenario, of which a family curse is the most rational, if that gives you any context for how out-there they are (they quickly stray into Illuminati murders and ritualistic sacrifice). People prefer to believe in that than that simple bad luck could be this cruel.