After Riggs escapes from being electrocuted, and then goes to save Murtaugh and his daughter, he obviously has no shoes on. He is shoeless throughout the next few minutes of chasing Mr. Joshua down the street, on the freeway, etc. Then, in a slow motion shot where Riggs is jumping down an embankment, some white tennis shoes magically appear! The shoes stay on him as he again runs down the freeway.

I just watched this. Riggs can be clearly seen wearing white sneakers before he even exits the bar where he was electrocuted. The shoes are on during the gun fight in the street, and during the entire chase.