These gentlemen were very lucky that no one we know of was hurt slamming on their brakes for an unexpected speed bump that wasn't there.
I find it to be a miracle that there are not more accidents and deaths on public roads every day. Traffic planning and civil engineering are generally not well performed where I live, and I've seen a number of actual speedbumps have awful unexpected environmental results (screwing up the drainage,) and fail to help traffic or safety.
These guys? No signs leading up to the speedbump from what appears to be the primary fast side? Again, seems lucky no one spun out.
This type of stuff never works out for Wylie Coyote.