Mestre

That could be cutting it too close. Have you already bought the train ticket? I ask because you have no way of knowing (or controlling) whether your flight will be on time or late.

If you plane is on time, If you are first off, if your luggage comes out in an early batch early.

google shows it a 15 minute car trip from airport to train station-- 20 minutes is reasonable baggage claim wait-- thats 35 of your 50 minutes --- do you have or will you need to buy train tickets?

it looks like you are one hiccup from disaster

Good news: No passport control as you are travelling inside the Schengen Area.
But deplaneing, walking, waiting for your luggage could well be over ½ hour. Too tight.

Are these trains hourly (most are)? In which case buy at the station, whenever you get there, and swallow the higher "walk up" price.

I recently tried to connect from Marco Polo airport to Mestre to catch a train. I didn't buy train tickets ahead of time, knowing I might be late. And the plane did arrive a little late. Then I took a ATVO express bus from the airport to Mestre - and that arrived/left the airport ten minutes late. And then the bus made an unscheduled stop before it got to Mestre (to let someone off - who knows why, I thought it was supposed to be an express bus!). I missed the train by about 2 minutes - I bought the ticket on my phone while I was on the bus, knowing it would be really close but decided to risk it because the next train wasn't for a few hours.

I'd say you are cutting it too close, especially if you have to collect luggage.

Thank you all for your input- kind of thought I was pushing the envelope. Will stay in Venice for 2 nights or head to Verona on a later train and stay there overnight. Have been to both of these places several times so do not want to linger too long.