A penalty converted in the 61st minute by Joseph Turner sent Slough stopper Jonathan North the wrong way to claim a well-earned point on the road.
The Rebels opened the scoring on 56 minutes through a well-crafted move between the lines, where Elliot Benyon opened his account for the hosts.
George Wells delivered a sumptuous cross from the left, which Benyon headed home leaving the keeper no chance.
The quickfire goals livened up a game which had struggled to get going. Josh Jackman had his right-footed drive palmed away by Jonathan Henly.
Tonbridge Angels also threatened in the latter stages, Craig Braham-Barrett sending a dangerous cross into the area, with the Rebels defence standing firm.
The first half was a different story, with both sides adjusting to the conditions with water breaks every 15 minutes.
Slough started the faster of the two sides and were unfortunate not to take the lead in the early exchanges.
Johnny Goddard delivered a teasing ball which Elliot Benyon flicked just wide under pressure, both the new signings making their Arbour Park bow.
It was a fractured first period with both sides struggling to take control; Slough played some nice passages of play, without overly threatening the visitors' goal.
As the game entered first half stoppage time, Slough ought to have taken the lead.
Benyon got himself in the right place at the right time to meet a dipping cross from Wells down the left, but his effort went whiskers wide of the post.
Overall, a draw was a fair reflection with both sets of players working extremely hard in tough conditions.
The Rebels' next fixture is Tuesday evening, where we host Chelmsford City hoping for a first victory of the season.
Image: George Beck
Tonbridge Angels Line up
Henly, Fielding, Braham-Barrett, Parkinson (Mason-Saunders (Collins)), Miles, Gard, Fagg, Turner, Akinwande (Walters), Taylor, Addy. Unused substitutes: Green, Manuel.