Seven people onboard a twin-engine Cessna 401 is close to that aircraft's weight limit; depending upon the amount of fuel.
If they didn't stop enroute for fuel, the fuel load would be reduced by the approx 2 1/2 hr flight.
Possibly pilot error, but I recall back in 1988 a couple of instances at our local FBO where C-401 exhaust system failures nearly causes fatalities. One was caught by a dedicated very thorough A/P. The other was caught in the act of burning through the firewall, shut down, and landed promptly. The 'Y' pipe below the turbo is hard to inspect without removing some hardware. Sometimes lazy mechanics don't do their job.