Mildenhall, who had earlier appeared to blame himself for Argyle's goal, dived to his left to keep out Marvin Morgan's header, leaving the substitute holding his head in disbelief.
"It was a save worth two points to us, just as much as the winning goal," said Ward. "Steve is an exceptional goalkeeper at this level, but more than that he is a great professional.
"If he makes a mistake he doesn't let it affect him. Had his concentration lapsed in the slightest he would not have made that save.
"The lads were all congratulating him in the dressing room. We now have a team of winners who are desperately trying for one another.
"I keep saying we need to look up the table and be positive. At half-time we had to reassess after conceding the equaliser, but I just told the lads to keep going and win the game again."
Kaid Mohamed headed the 78th-minute winner from a Lee Brown cross at the far post to settle a competitive game at the Memorial Stadium and maintain Rovers' climb up the table.
The hosts went in front after seven minutes when Mohamed nodded on a Michael Smith long throw and Chris Beardsley stooped to head in off a post.
Rovers had chances to increase their lead before Argyle hit back on the stroke of half-time. Mildenhall could only block a Luke Young free-kick and Michael Blanchard headed the loose ball across goal for Neal Trotman to nod home from close range.
Plymouth's goal had led a charmed life two minutes earlier when in a matter of seconds Tom Parkes had a header saved, Ollie Clarke saw two shots blocked, Brown had an effort cleared off the goal-line and David Clarkson blasted into the side-netting.