Expedia is more than happy to sell you a ticket with an 'illegal' minimum connection on a single ticket (and on a single airline). I believe that if you just search for a flight (A-B) then Expedia has a guarantee that it won't breach minimum connection times. However, if you search for a flight with multiple connections (A-B-C) for whatever reason then it is down to you to make sure the connections are valid.

I had a flight last year where I searched A-B-C (to get a low fare) and ended up with an illegal connection ... Expedia wasn't interested in helping me ... luckily it all turned out fine and I learned my lesson