But Adkins reckoned his side battled well against a side who are among the favourites for the title this season.
"We put up a good show and will try to take the positives," he insisted.
"Watford have come to the fortress and laid siege. We showed fantastic character not to be bullied by them.
"I was disappointed with the second goal because that changed the complexion of the game.
"They then got that breakaway goal that dampens the game down for us. We tried to force the issue, but it wasn't to be.
"It was mission impossible and we've proved that whoever comes here will need to be on top of their game to get the points.
"The fans have seen a totally committed bunch of players giving their all."
Watford were relegated from the Premiership last season, and their boss Aidy Boothroyd relished a visit to Glanford Park rather than Old Trafford.
"I was excited about coming to this place because it's a proper club," he reflected.
"We've tasted the prawn sandwiches at the big corporate clubs and I'm sure Scunthorpe will do ever so well.
"We knew it would be difficult but we coped with what they had and won.
We've played exceptionally well in spells in all our games but not so good in some of them. But for long periods this week I thought we were outstanding."