Orebotse Mongae opened the scoring at the Mbombela Stadium on 29 minutes ahead of a Bernard Parker goal a minute before the half-time break.
Sphiwe Mahlangu made sure of the points with his strike with 56 minutes on the clock, but there was no let up from a rampant Rockets who completed their demolition of Arrows with an 86th minute Nkosikhona Radebe goal.
The result saw Galaxy move onto 22 points in 10th place, four points clear of the relegation places.
Arrows are a place worse off in 11th but with the same number of points.
Chippa United, meanwhile, recorded an important three points following a run of poor form with a narrow 1-0 victory over an improving Maritzburg United.
The Chilli Boys were without a win in seven league games while the Team of Choice had won their last three encounters.
Etiosa Ighodaro netted the only goal of this tie, at the Nelson Mandela Bay Stadium after 58 minutes, to leave his side in seventh with 24 points from 19 games and Maritzburg down in 14th with 20 points.
Elsewhere, Richards Bay were held to a 1-1 draw with AmaZulu where Katlego Maphathe's 94th minute effort cancelled out Thabo Qalinge's 33rd minute opener.
The Natal Rich Boyz remain second, two points clear of SuperSport United with 31 points from 18 games as Usuthu sit in eighth place with 23 points.