The Tudors had thrown themselves right into the mix after they had claimed a fine 1-0 victory over Hampton & Richmond Borough at Vauxhall Road on Good Friday.
But they were unable to follow that up in the second part of their Easter double-header as a freak own-goal from Gus Scott-Morriss and a second-half Josh Jackman strike sealed the points for Slough.
Hemel’s misery was compounded by second-half red cards for Dan Wishart and Cole Kpekawa.
The Tudors return to action on Saturday with a tough home clash with leaders Maidstone United.
Reflecting on Monday’s loss, boss Jones told the club’s YouTube channel: “I don’t think we played particularly well but you have to give the opposition credit, they caused us a few problems.
“The first goal we conceded was just a freak, I didn’t really see it until it was just trickling towards the net. When you concede a goal like that you wonder whether it’s going to be your day.
“But we had enough time to come back into the game. Slough had a lot of possession but I didn’t think they really hurt us and we’ve had moments in and around their box.
“We had a bit of a gamble at half-time, I felt we needed to win and we went to 3-4-3 but we didn’t really create a lot of clear-cut chances.
“The little details we didn’t get right but the main incidents in the game didn’t really fall for us.
"The red cards cause us a bit of a problem because they will both be banned for three games and they are both naturally left-sided defenders.
“My record at Slough as a manager is pretty poor, I don’t think I’ve enjoyed a good day there! It’s a difficult one to take.
“It certainly wasn’t our day. I didn’t think there was a lot in the game.
"I fancied us to keep going and get something out of it.
“It was a keenly-contested game between two similar sides and they have come out on the right end of it.
“In my opinion, there wasn't loads in the game but we didn’t produce a performance good enough to get three points.”