The 22-year old striker took his tally to eight strikes in nine Super Premier matches as the Possil-based outfit staged a rousing comeback after finding themselves 2-0 down with only 20 minutes played.
And Hall was on a hat-trick after he rounded Rabs goal- keeper Stephen Robertson just outside the penalty area.
But he was prevented from having a shot at goal by the experienced stopper deliberately handling the ball.
Rankin said: "Chrissy's overall play was outstanding. His second goal alone would have graced any level of football.
"He was up against two very experienced central defenders yet they struggled to keep tabs on him every time we were on the attack.
"It's a crying shame he was denied a hat-trick. The ref said two Rob Roy defenders were in the vicinity, but they were both running back wide of the incident towards their own goal and could not have stopped Chris shooting into an empty net.
"So if the keeper's deliberate handball is not denying a goal-scoring opportunity what is ?"
That 70th-minute talking point was one of many in a thrilling game that kicked off with Rob Roy on the ascendancy.
And it was no more than they deserved when their best player Kevin Bradley glanced home an inswinging Kieron McAleenan corner kick for 1-0 .
They doubled their advantage when Stevie Meechan rifled in a 22-yard shot that appeared to catch Ashfield keeper Stephen Hall unawares.
And a rattled Ashfield were then fortunate not to concede further goals after Iain Diack was twice put clean through on goal only for Hall to foil his scoring attempts.
The home side began to threaten and halved their deficit just after the half-hour mark when Hall rose unmarked to direct a downward header past Robertson following a terrific run and cross by Gary McCann,
Hall, though, had kept the best for last. Midway through the second half, he took possession just over the halfway line and set off on a run, skipping past three Rob Roy defenders in the process, before unleashing a 22-yard shot high past Robertson for 2-2.
Hall said: "The goal just opened up for me and I decided to have a pot that thankfully found the net because one or two team-mates had run into good positions and were screaming for a pass.
"It was a really enjoyable game to play in and I felt a lot happier when Stevie pushed me further up when we were trailing 2-0."
The Kirkintilloch outfit's latest slip-up would appear to have finally put paid to any Super Premier title hopes after word came through that the third placed Rabs had lost further ground on leading pair Auchinleck Talbot and Petershill who both posted crucial victories.
Table-topping Talbot emerged 1-0 winners at Bellsdale Park thanks to a James Latta strike.
Nearest challengers Petershill chalked up a resounding 4-0 victory over a nine-man Arthurlie.
In other top flight contests, Ryan McCardle came off the bench to net an 88th-minute winner to help Pollok triumph 1-0 at Glenafton while a notable first league win of the season was chalked up by Shotts Bon Accord away to Clydebank.
It was all change atop the Super First Division pile after Hurlford United regained pole position through a 3-2 defeat of Maybole at the same time as previous leaders Largs Thistle crashed 3-1 to Kilsyth Rangers.
Up into third spot are Kilbirnie Ladeside, who recovered from going 1-0 down to score four second half goals to sink Cumbernauld. Meanwhile, John Paul Craig bagged a hat trick as Glasgow Perthshire routed Ardrossan Winton Rovers 6-0.
However, the day's scoring honours belonged to Renfrew hitman Chris Zok who netted four of his side's goals in a 6-2 defeat of Rutherglen Glencairn.
In the District Leagues, Greenock opened up a ten-point gap on the chasing First Division pack thanks to a 3-0 home win over Dunipace at the same time as second-placed St Anthonys were held 1-1 by Lesmahagow.
Cambuslang Rangers remain Second Division frontrunners after a 7-0 drubbing of Royal Albert.
There were celebrations at Fullarton Park where Blantyre Vics chalked up their first league win of the season in beating Vale of Clyde 2-1.
Kilwinning Rangers moved 13 points clear atop the Ayrshire set-up after overcoming Annbank United 3-1 while closest challengers Troon suffered a surprise 2-1 defeat by Ardeer Thistle.
And hats off to centenary celebrating Cumnock for securing a last-16 place in the Emirates Scottish Junior Cup through a 5-4 fourth-round triumph away to Culter.