It highlighted a stellar game by McGuire who may be a Kangaroos bolter when the trans-Tasman team is named on Sunday night after his 38-tackle, 127m effort.
Hat-trick hero Bureta Faraimo kept the Eels in the match, scoring his second off a classy Corey Norman pass in the 55th to limit the damage to 14-10 before a Corey Parker penalty.
Then Brisbane's Kodi Nikorima surprised everyone - including himself, no doubt - when he looked to rue a golden chance, only for his last gasp backflick pass to set up Milford's 62nd minute try.
Faraimo secured his hat-trick in the 70th minute moments after Eels skipper Tim Mannah was somehow held up by Nikorima before Milford's late heroics iced the result.
Brisbane led 8-4 at halftime thanks to a 15th minute Jack Reed try and two Parker penalties.
The only blight for McGuire was being placed on report for a 15th minute high shot on Brad Takairangi.
Eels lock Anthony Watmough was also booked for high contact on sensational Broncos fullback Lachlan Maranta in the 58th minute.
- AAP