In the later episodes, the cut marks on Ken's arms disappear and re-appear between frames.
When Ryu and Chun-Li had the cyber chips planted to their foreheads, you can easily tell that the sizes vary between frames.
For those that are not familiar with the Japanese language. Ryu's name is pronounced (Ree-you), not (Rye-you). Also Ryu is a direct translation meaning Dragon in Japanese, thus making Ken's and Ryu's signature move Sho-ryu-ken literally translating Rising Dragon Punch.