I fixed the line, it seemed that even though I thought and it indeed looked like the tiles were flush with each other, turns out there was a very small gap and you could see it once the level started to scroll.
Ah. Also bear in mind that the positioning of objects gets less and less accurate, the further they're positioned away from 0,0,0. I trust you've got a fixed camera position and achieve scrolling by moving the tiles? I added a water plane to the river tile, set its name to water in Max, and then thought I could use findchild to get it and set its alpha but that didnt work. findchild didnt find anything in the mesh.
Did you use LoadAnimMesh, instead of plain LoadMesh?