The team probably did find something interesting, but it's more likely leftover metal junk from previous searchers than actual treasure. Call me crazy, but if they had actually found something of great value and/or significance, wouldn't they have promoted the hell out of this season? There's no way they'd keep any significant find hush hush until the last episode instead of spreading the word "to please tune in, because after 200 years, the mystery of Oak Island has finally been solved."
Another possibility is that they did find a metal contraption deep underground, did their best to try and open / retrieve it (or send divers in to inspect it), but had to halt further inspection until after the winter season. In their minds they may have concluded that they did actually find the original vault, which is why there's been reports of internal arguments, but in reality come next spring, it'll likely turn out to be an an old metal chamber constructed during the 1860's as part of the search effort. Also, unless the "steel trap" is located outside the money pit area, or is deeper than 140 ft, Dunfield would've surely dug it up and threw it back in back in the 1960's.