"I thought we were in control for large parts of the game,” Cass said.
"In the first 30 minutes we should have been 4-0 up.
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"We just had a strange 15 minutes, five minutes before half-time we lose a goal and 10 minutes after the restart we had lost another three goals.
"It was a crazy 15-minute spell for us and silly goals for us to give away unfortunately.
"After that we took control of the game again and pushed to try and get goals back.
"It was a strange one and obviously bitterly disappointing to lose the way we did.”
Things seemed to be going swimmingly for Rovers on Sunday as they hit Berwick with those two goals inside the opening quarter of an hour to go 2-0 ahead.
Their first strike came on five minutes when Arron Darge’s corner ended up flying straight into the net and it was 1-0 Rovers in sensational style.
Zander Murray then got into a great position in the box for Rovers but shot into the side netting.
But things did get even better for the visitors on 15 minutes when another corner was diverted into the home net by Murray.
The passions of derby day then boiled over as Gala’s Liam Campbell reacted to a hard Michael Travis tackle by kicking him in front of the assistant referee. But it was decided that a yellow card sufficed for both players.
Darge then sent an ambitious long ranger just past the post on 31 minutes, before the same player connected with a low cross but home keeper Alasdair Adams saved.
Sean Stewart then headed over a Harris free-kick from the left, but the home team did pull it back to 2-1 on 41 minutes when Travis headed in a Stewart cross.
Just two minutes into the second half it was 2-2 when David Ferguson lashed the ball home after Gala keeper Harris Spratt had dropped a corner.
And the incredible turnaround continued on 52 minutes when Spratt brought down Stewart at the expense of a penalty scored by Alex Harris.
It was then 4-2 for the hosts just five minutes later when Graham Taylor scored with a deflected, looping shot.
The final action came on 77 minutes when Murray got in behind and launched a fierce strike which Adams did very well to tip past the post.
Rovers, ninth with 30 points from 20 games, host Vale of Leithen this Saturday in a New Year league derby, with kick-off at 3pm.
"It’s a derby so it’s always a tough game,” Cass said. “Credit to the Vale, they have picked up.
"Even when we played them the last time we never took anything for granted and we would expect the team that we play – whether they’re top or bottom of the league – we will always give the teams the same respect.
"It will be exciting for the fans and it would be great to get a win and get back on that winning streak we showed earlier in the season.”