strong flashes at the beginning of the movie (kickboxing fight) lots of old flash photography (sometimes towards the screen).
Some mild flashing at the tabledance-bar. You see JCVD and another person entering the bar, and you could look away from that moment on to avoid flashes.
JCVD pops up from a pool and asks if he’s done yet, and his coach tells him he has to keep training under water and pushes his head. It is pretty playful
There is a brief scene in the third act. A woman is kidnapped by two men who her up a ramp to meet the main villain. It seemed clear what was going to happen, and I looked away for maybe 10-15 seconds.
[MAJOR SPOILER] After the first Kickboxing Fight you will see, the loser is heavily injured. They take him to a hospital. No surgery or something like that is shown after, but some of the protagonists talk with doctors in the hospital.