The West Yorkshire club ran their illustrious rivals close in their opening Qualifiers game yesterday before eventually succumbing 14-0.
Halifax, the lowest-ranked team in the competition having finished fourth in the Championship, had plenty of chances to hurt their opponents who led just 8-0 heading into the closing stages.
But Marshall conceded: “Our execution let us down today.
“We had plenty of opportunities and created lots but in strong positions and at key times we just came up short.
“There was a little bit of a hangover from the last three or four games (of the regular season) as we’d been a bit nervous with the ball there, too.
“If we’d have got to half-time at zero-zero (instead of 0-6) we’d have adjusted better.
“But then they got that penalty goal and we couldn’t get there despite a great effort.”
Marshall believes his side – the only part-time team to reach the Qualifiers – actually won the “physical battle” with Toronto, who have plenty of Super League talent in their ranks.
“Toronto defended really well,” he added. “(Full-back) Gaz O’Brien kept showing up everywhere to deny us and we got over the line a couple of times.
“Some kicks just didn’t sit up and we couldn’t sustain the pressure we wanted to.
“The margins are a lot finer in this competition. I thought we probably won the physical battle.
“We were really good; Toronto have a couple of busted bodies – we wish them well – and we really gave it to them at key times. But that’s not enough at this level. We are good value for what we are though; remember, out of that 19-man squad nine players were born in Halifax or came through our Reserve Grade. We work a different template to Toronto.”
Halifax head to Championship rivals Toulouse Olympique on Saturday hoping to have Simon Grix back from injury.
Toronto fear they have lost Liam Kay (ankle) for the rest of the season while Matty Russell came off with concussion.