Paul Sackey tries to stop England's Steffon Armitage
England manager Martin Johnson said his side must become smarter after suffering a second-half collapse in the 35-26 victory over the Barbarians.
England led 32-7 shortly after the break but their opponents hit back to set up a tense finish at Twickenham.
"The game became loose at times and there's a danger that you'll get sucked in and lose shape," said Johnson.
"We have got to be smarter and shouldn't have gone into some of the areas that we did."
The win ensured England head off on their tour of Australia and New Zealand on the back of a victory but Johnson expressed concern over the number of penalties his side conceded at the breakdown.
He added: "In the second half we lost our way and got penalised a lot and we didn't keep hold of the ball.
"The Barbarians chanced their arm at the breakdown and I'm not sure it would come off in a Test match - the referee obviously saw the game differently.
"If they do that and you can't slow them down then there will be chances.
"There were some very good things in the first half and we got away from them a few times.
"I said to the players these can be difficult games sometimes, there's occasionally space there when you don't expect and you end up throwing a few balls that you wouldn't normally throw.
"The Barbarians were always going to be dangerous, particularly when they had nothing to lose."
Sale fly-half Charlie Hodgson left the pitch in the first half after suffering a bang to his face but it is not thought to be serious, while Newcastle prop Jon Golding sustained a rib injury.
Barbarians coach Philippe Saint-Andre revealed his side's social commitments this week contributed to their poor display before their late revival.
"It was a very good second half. In the first half we were still in the discotheque." said Saint-Andre.
"We had a lot of players from European winners Cardiff and Toulouse who have been celebrating and they weren't quite there in the warm-up.
"In the end we played a good game of rugby and played like the Barbarians.
"England face a tough tour but they will have taken confidence from winning this game."
Saint-Andre, the Toulon coach, revealed Jonny Wilkinson should be available for the first Test against Australia on Saturday week after recovering from a rib injury.
"Jonny will need one week's rest but he will be fine for the opening Test," he said.