Joint manager Neil Baker summed things up after the game by saying that "everything that could go wrong did go wrong", with Jon Underwood bemoaning a lack of quality from his side.
Weymouth almost scored early on as Adam Kelly burst forward into the area and cut the ball back for Chris Shephard, who blazed over.
The Terras poured forward, pinning Slough in their own half, and Shephard fired a dangerous free kick into the wall. The Rebels tried to create chances of their own, with Andy Dawber coming out to clear from Charlie Mpi and punching a corner clear.
Nathan Webb was forced off with an injury after just 14 minutes and was replaced by Kensley Maloney, with Slough having to reshuffle.
Dean Evans was teed up nicely on the edge of the area, but his low drive was easily held by Mark Scott in the Slough goal.
The Terras' pressure paid off with the opening goal on 29 minutes as Evans rifled a left-foot strike into the top corner from 25 yards.
Within three minutes, Weymouth had a second goal. Ben Thomson followed up to score from close range after Mark Cooper had burst forward into the box and lofted the ball over Scott.
And the Terras started to run riot, taking a three goal lead on 34 minutes. Weymouth charged forward again through Adam Kelly, and he found Shephard, whose deep cross found Thomson again, who smashed the ball into the roof of the net from close range.
With Weymouth dominant as the first half ended, Shephard came within inches of making it four after he latched on to Kelly's cross but shot across the goal and wide.
Slough's afternoon went from bad to worse just 90 seconds into the second half as Shephard got the goal his performance merited, sliding the ball into the bottom corner from the edge of the box.
Dawber was then almost caught out as he tried to take the ball past Mpi, but Slough's top scorer was unable to turn the ball home and Calvin Brooks got back to clear.
Weymouth's fifth goal was again far too easy as Slough were carved open yet again. In probably the best move of the match, Shephard fed Mark Cooper, who worked his way into the box and found the top corner past the helpless Scott.
And with just 67 minutes played, Weymouth made it six as substitute George Rigg burst past Dan Hicks in the left channel and finished neatly.
Shortly after, Kensley Maloney was shown a straight red card after reacting following a challenge with the Terras' Aaron Moody.
Slough's only bright spot of the match was a goal from Eddie Smith, which takes him to a total of 90 for the club in just 140 appearances. The Rebels worked the ball well around the box and the ball broke for Smith, who pounced to slot the ball past Dawber with 12 minutes remaining.
Weymouth Line up
Andy Dawber, Mark Cooper, Jordan Copp, Dean Evans, Chris McPhee (c), Calvin Brooks, Adam Kelly, Billy Lowes, Mark Molesley (George Rigg 58), Ben Thomson (Stewart Yetton 66), Chris Shephard (Jake Wannell 71). Subs not used: Ashley Wells, Tim Sills.