_ 7:03 p.m. Sunday: Air France says plane left Rio de Janeiro. Brazilian Air Force says plane left at 7:30 p.m.
Possibly a numerical transposition error or more likely the usual confusion of 'out' versus 'off' time. Years ago some wacko wrote a conspiracy theory book about the Lockerbie crash and used this discrepancy to help 'prove' his conjecture.
The final ACARS messages were sent well out of VHF range it appears, they would be sent with HFDL or Satcomm. HFDL messages can be read thousands of miles away and normally contain position data, I've used Charles Brain's PC-HFDL program to track planes off the coast of Africa from the U.S. with a computer and HF receiver.