The projectile issue requires retrofit's descr_projectiles and possibly some files if it uses a non vanilla model. Or replace the projectile with a vanilla one.
The mount issue requires retrofit's modeldb file and possibly mesh and textures files for the battle model(s) in question. BG doesn't need a descr_mount file - it uses\refers to the vanilla default file. You will however need it as you will otherwise get EDU errors for unknown mounts.