Mitchell is currently slated to start at right tackle, but the Bears would prefer to upgrade the position through free agency.
Miller, 32, could help bridge the gap between Mitchell being ready to start or give time for a tackle to develop if the Bears decide to take one in the draft.
However, if the Bears sign one of the top free-agent quarterbacks they probably cannot afford the 6-foot-7, 320-pound Miller.
Kurt Warner will be in Detroit Sunday and Monday with a decision between the Bears, Lions and Cardinals likely to come later in the week.
Fiedler is slated to visit with the Bears in the coming week, as is Brad Johnson.
The Bears are a long shot to sign Warner because the other competitors offer more talent and a better chance to start.
Fiedler and Johnson would be more willing to accept a supporting role, come at a cheaper price and could leave enough cap room to also sign Miller.
The Bears are also talking to the Cardinals about tackle L.J. Shelton, but the two teams have not been able to agree on compensation.