Maynard attracted the attention of umpires in the second quarter of the match at Giants Stadium for making late contact with GWS forward Daniel Lloyd.
Counting against the 25-year-old will be the health of Lloyd, who was ruled out of the rest of the game following the incident.
It was not the Magpies' only concern ahead of their season-opener against St Kilda on March 18, with recruit Patrick Lipinski suffering an ankle injury.
Lipinski, the former Western Bulldogs player, had looked comfortable in Collingwood's midfield after his off-season move.
Nathan Murphy's injury looked to be even more serious, with the defender hobbling off the ground in the third quarter with a leg issue.
The Magpies showed some good signs in their final pre-season hit-out, but the Giants ultimately prevailed 15.10 (100) to 8.11 (59).
Dynamic star Jordan De Goey made an encouraging return after missing last week's match against Hawthorn in Morwell.
The Magpies look to be persisting with De Goey more in the midfield than the electric forward he was for most of his first seven AFL seasons.
Nick Daicos, the Magpies' top selection in last year's draft, will surely be picked for his AFL debut in round-one after gathering a club-high 31 possessions.
For GWS, young prospect Conor Stone (hamstring) might join Lloyd in being unavailable to start to the season after failing to play out the game.
The Giants will be without superstar forward Toby Greene for the Sydney derby against the Swans on March 19, but look to have enough scoring options.
Jake Riccardi and Bobby Hill, whose trade request to Essendon in the off-season was knocked back, booted three goals each.
Midfielder Tim Taranto fired by collecting 31 touches and two goals, while Josh Kelly was prolific with a game-high 41 possessions.
Injury-prone ruckman Braydon Preuss made a rare appearance and the Giants will be desperate for him to stay fit after the retirement of Shane Mumford.
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