Orient were unbeaten at home in six months when the Glovers arrived at Brisbane Road, but Matthew Spring saw an early red card as the hosts crashed to a 5-1 reverse.
Slade branded the defeat a "freak result" and has backed his players to get it out of their systems at The Valley on Saturday.
"We'll try to learn from that and for it to make us better," he said.
"There's always lessons to learn. Of course, it will be a tough one at Charlton."
Source: PA
Source: PA