Furniture casters are likely to separate from furniture during the move. So just go ahead and remove them before transport. You can tie them together with heavy twine and tag them with the name of the furniture piece they belong to. The same thing goes for framed pictures and mirrors. Some framed items come with special screws and hanging devices that you don't want to get lost in the shuffle during the move. Save those devices in a plastic bag and either tape the bag to the mirror or frame or store the bag separately with tags that indicate which hanging devices go with which frame.