OUCH!
Most often the on-board converter/charger unit is the first thing that blows... Most folks lose controllers for their fridge, microwave unit, and air conditioner units. Hopefully your optional 50AMP system protection electronics may have saved a bunch of high dollar failures...
Most trailers are wired for 120VAC. The 50AMP RV is usually just two zones of 120VAC... A very few of the high-end RV Motorhome/trailers actually use 220VAC for the built-in Clothes Dryers.
Most of the time it takes about $3000 dollars to get everything back to normal working order when this happens... Immediately pulling the cord out is not fast enough. That stuffs travels at the speed of light....
You hear alot of this when the local unknowing Electricians are hired to wire up pedestals for the RVs... Thank goodness the good ones are bonded and have insurance.
Roy Ken