The hit left Goodwin on the field for several minutes before he was carted off the field.
Goodwin dived for a ball that was out of his reach. Countess launched himself to where Garoppolo's pass would have met Goodwin's hands and popped Goodwin's head.
"It's unbelievable the safety did that," Garoppolo said. "That's not good for our sport, it's not good for anybody.
"It's just a dirty play. But, it's football. I mean, it happens."
Goodwin gave a thumbs-up sign with both hands as the cart took him toward the tunnel and away from the field.
Countess was flagged for unnecessary roughness, which moved the ball to the Rams' 8-yard line. On the next play, 49ers running back Carlos Hyde took a handoff up the middle, was stopped at the 5-yard line, but a massive push by what looked like the entire San Francisco offensive line, and perhaps a tight end and a receiver or two, helped push Hyde across the goal line for a touchdown.
Were the 49ers extra motivated on that play?
"Hell, yeah," Garoppolo said.
"The offensive line wanted to make a statement," Garoppolo said. "Carlos and everyone was fired up. We wanted to do it for Marquise, I think."
--49ers linebacker Elvis Dumervil got a milestone sack in his team's 34-13 win over the Los Angeles Rams.
He now has a sack against all 32 NFL teams.
"I'm honored," said Dumervil, who concluded his 12th NFL season. "It's a difficult thing to do."
Dumveril joined the 49ers in 2016. He previously played for Denver and Baltimore.
--Rams running back Todd Gurley II was the NFL's leading rusher going into Week 17. He did not play Sunday, which probably cost him the league rushing title.
And Gurley was fine with it.
"Congratulations to him," Gurley said. "He deserves it."
Gurley remains a chief candidate for NFL MVP honors.
"Vote for me, vote for me please!" said Gurley, kiddingly. "If not, then it's all good."
--Rams cornerback Kevin Peterson made the most of his first NFL start.
He had two interceptions Sunday.
"Yeah, that's awesome," Peterson said. "I'm really more mad because I feel like I made some worse plays than the interceptions, so I didn't really get a chance to celebrate those."