A CRJ-700 flight crew returned to their departure airport when they received anomalous gear safe indications following takeoff.

Narrative

After takeoff I selected gear up and nothing happened. About 5-10 seconds later we got a GEAR DISAGREE WARNING. The First Officer (pilot flying) called for speed mode; heading mode; autopilot ON. As I was reaching for the QRH the gear safe lights started going berserk: 3 green; 3 yellow; 1 green; 2 yellow; 2 green; 1 yellow; etc. and the nose gear sounded like it cycled up and down 3 or 4 times.With gear lever down indications were three green and the nose gear stopped cycling up and down. Question was; can we really trust the 3 green indicators? We decided to do a flyby and get some outside help. On the first pass we used flaps 20 setting thinking any more would interfere with viewing the gear. As we passed by the EMS leader said it 'did not look like the nose gear was down 90 degrees.' Following a second pass; this time by company personnel; everyone was in agreement that the gear was; in fact; down. We made a wide pattern back around to get ready for landing.Throughout the event; I made numerous communications with Maintenance; the flight attendants; ATC; and PA's to the passengers. We reviewed the QRH for the Gear Disagree Down and Up Procedures and the Landing Gear Up/Unsafe Landing Procedure. The manual extension handle was fully stowed and the gear pins were stowed behind the First Officer's seat. I asked the First Officer if he was comfortable as the flying pilot or if he wanted me to take it. He said he was good and I had no reservations about his piloting skills. Landing was very gentle and we let it roll to a stop on the runway where gear pins were installed and the aircraft was towed to the gate. We landed overweight; touching down at 69;000 LBS. I entered discrepancies in the logbook for the gear disagree and the overweight landing in coordination with Maintenance Control.