All anal play - whether in a forced role play or not - should involve adequate warm up and plenty of lube to avoid the potential for injury.
More About Forced Anal
It is important to remember that forced activity scenes are just that - scenes. They must be negotiated beforehand and the partners must agree on which activities will and will not take place. Safe words must be established so that either partner can stop the scene if they feel unsafe or are no longer into it.