No, don't remove the UntrackedVariables.
As far as I can guess there can be other minor compatibility issues between file generated with MMA 10 and the previous versions of CDF Player (apart from the reknown UndoTrackedVariables).
Another issue could be the graphics options since the color schemes changed heavily from v.9 to v.10. So you could try removing the non standard displaying options.
You could also ask the people who see the "pink" screen what version of CDF Player have installed (maybe they are on a way older version) and if, hovering on the pink image with the mouse, they see some tooltip describing the error.
Luca