That sounds like lag on their end, too. One of my linkshell mates had a while where her internet was terrible, and she was doing things like that. One time she died, but it didn't register on her end. She ran halfway down the map, and for the rest of us, it looked like her KO'd character was just sliding across the ground.

In LL, I've also seen people's characters show up on the wrong level. To them, they are on ground floor, but to me, it looks like they are on the second floor. Could that explain your example?