No wires or CG work were used in the fights.
Tony Jaa trained extensively in the ancient form of Muay Boran (the predecessor to Muay Thai) for four years in preparation for this film.
'Ajarn Yodthong' (a great master of Muay Thai) makes an uncredited appearance as the man selling cigarettes. This can be seen when Ting fights in "The Pub" for the second time.
Many of the "bad guys" had weird hairstyles to hide their head padding. During the-slow motion scenes you can see them angle their heads downwards to catch elbows on the tops of their heads, presumably where the padding was thickest.