Fullback Walsh was on the bench with ice on his right knee after halftime at Kayo Stadium in Redcliffe on Saturday, but the early word from the Broncos was that it was not serious.
Staggs, who has had calf and hamstring issues in the pre-season, left the field in the 13th minute with a quad complaint. The Broncos took no chances and he did not return to the paddock.
Prop forward Haas was off five minutes later with an ankle twinge.
There was initial concern from the Broncos bench considering he'd had an ankle clean-out in the pre-season. Haas sat on the bench for the rest of the match, but did not return.
AAP was told Haas had to change the orthotics in his shoes but was otherwise OK.
The Broncos confirmed all three would be right for round one.
"I'm sure they'll be fine," winger Jesse Arthars said.
"They're very important. They're obviously our leaders, so we look to them when it gets tough. Payno likes to lead from the front and we're going to need him in the season.
"We wanted to start hitting the ground running. We've had a really good block in the pre-season."
The Broncos are set to win the NRL Pre-Season Challenge for consecutive years. They were steely in defence early to repel the Bulldogs, and strong with the ball, with lock Kobe Hetherington, prop Pat Carrigan and hooker Cory Paix standouts.
Star recruit Ben Hunt had a hand in all three first-half tries, before coach Michael Maguire rested his big guns after the break.
Bulldogs fullback Connor Tracey had an unhappy afternoon, with two spilled bombs leading to tries.
Half Toby Sexton and second-rower Jacob Preston were strong, but Canterbury were sloppy with and without the ball.
The influence of Hunt was on show early, with a deft kick that was bobbled by Arthars over the tryline.
Brisbane opened the scoring with a try to skipper Adam Reynolds, who picked up the scraps after a precision bomb by Hunt was dropped by Tracey.
Hunt was influential in the second try, holding up a pass that was burst on to by Walsh, who showed composure to send Arthars over.
Hunt sent half Jock Madden into space for winger Selwyn Cobbo to finish and give the Broncos a 14-0 lead at halftime.
Another Tracey error gifted Broncos centre Delouise Hoeter a try after the break.
A 60m burst from dummy-half by Preston for a cracking try lifted the Bulldogs, who added a second to winger Ratu Rinakama after slick work from five-eighth Matt Burton.
Bulldogs winger Blake Wilson reduced the lead to four, before Brisbane centre Deine Mariner and giant prop Ben Te Kura scored to ice the win.
Canterbury forward Josh Curran was put on report and sin-binned for a high shot on Jack Gosiewski.
