Farnham were 3-0 down with 10 minutes to play and their two late goals only served to make the score a little more respectable.
Godalming got the perfect start when, with just seven minutes gone, Chris Edmonds' clearance cannoned off Tommy Moorhouse who then calmly shot into an empty net.
Moorhouse, Godalming's new signing from Corinthian Casuals, went on to score a hat-trick and always troubled Farnham with his skill and strength on the ball.
But despite that early setback, Town seemed certain to at least level the scores before half-time.
Edmonds' long down-wind clearances, with the ball bouncing steeply off the hard, uneven Memorial Ground surface, was the stuff of nightmares for the Godalming defenders. How Farnham failed to score, only they will know.
Once, goalkeeper Dave Tidey rushed out to help his panicky defenders, only to be outjumped by Alan Morgan whose header drifted wide of an unguarded goal.
An even better chance fell to Graeme Miles who was completely clear after another massive punt by Edmonds. To Farnham's disbelief, the striker shot high and wide from no more than 10 yards and with not a defender in sight.
In between, Matt Edwards' sweet volley from a Scott Hooper corner brought a superb flying save from Tidey.
It was all Farnham and so it was a disastrous setback when Godalming scored in the third of eight minutes of injury time played by referee Brian Fish.
With the home defence in disarray, Castleman hit a low cross from the left and Shaun Lydon nudged the ball into the far corner.
Manager Andy Nunn boldly sent on a third attacker, Kevin Annetts, for the second half, but Godalming had the bit between their teeth now and could have doubled their lead in the first 15 minutes, with Short hitting the bar and Lydon shooting straight at Edmonds when it seemed easier to score.
Farnham were under the cosh and conceded the decisive third goal on 65 minutes. Edmonds and Matt Wheeler made brave blocks at the expense of a corner and James Blason's kick picked out an unmarked Moorhouse who placed his header to perfection just inside the far post.
Miles has been something of an enigma for Farnham this season. He doesn't always punch his weight, so to speak, and was often statuesque and ineffective in this match.
Yet his two late headed goals were right out of the top drawer.
Edwards took a corner in the 80th minute and, with Annetts making a decoy run, Miles charged in to score with a crashing header.
Godalming replied with their fourth when Wheeler tripped Moorhouse who got up to beat Edmonds with an audacious chip from the penalty spot.
There was still time for the lively Annetts to measure a fine cross from the left and Miles bent low to direct a lovely glancing header into the far corner.
Farnham: Edmonds, Brooks (Annetts 45 mins), Williams, Moore, Decicco, Wheeler, Sporton, Edwards, Miles, Morgan, Hooper (D Brown 67 mins). Sub (not used) Blake.
Godalming: Tidey, Steer, Castleman, Bowditch, Flynn, Clarke, Blason, Short (Elliott 73 mins), Moorhouse, Lydon (Hawkins 66 mins), Ray (Stanley).