Engines 2 + 3 gave spurious thrust reverser unlocked indications at rotate leading to an automatic slat retraction with associated loss of lift.
Crew handled the amber thrust reverse warning with full thrust and gear retraction with onset of stick shaker.
Aircraft flown away and returned to JNB after dumping fuel.
Excellent handling of the situation by the crew who contained an extremely serious incident.
As has been mentioned before a Lufthansa aircraft which tried to get airborne from NBO didn't make it when the LE Slats weren't deployed so it shows the quick thinking of those involved.