Spagnuolo joked on Sunday, a day after St. Louis beat Indianapolis 33-10, that he wasn't sure if referees weren't interested in dragging the game out.
The Rams and Colts played a penalty-free first half. The Rams finished with 14 penalty yards and the Colts had only one call for 5 yards.
"Very encouraged by that," Spagnuolo said on a conference call. "I hope it continues. I hope it doesn't mean the officials were trying to get home early."
Avoiding mistakes has been an area of emphasis during training camp, and Spagnuolo said that's the case with every coach. But he couldn't have anticipated such a clean start given mistakes made in practice.
"We've had our share of false starts," Spagnuolo said. "When you have penalties you're just beating yourselves. The balance is being aggressive and yet disciplined, and it was encouraging to see that it didn't hurt us."
The Rams didn't allow a sack and capitalized on two early interceptions against Colts backup quarterbacks for 10 points and later forced a third turnover.
The offense scored on six of the first seven possessions, was 8 for 17 on third down and totaled 169 yards rushing without Steven Jackson.
Josh Brown put the Rams up 23-3 at the half with a 60-yard field goal that would have been a franchise record if it happened in the regular season.
"It's the preseason, that's what makes you want to do that," Brown said. "I mean, we're indoors, and we had the opportunity. I hit a lot this week over 60.
"If only it counted, you know."
St. Louis had the edge in time of possession, holding the ball for 36 minutes and 17 seconds, and was 3 for 5 scoring touchdowns inside the 20. The Colts were held to 2 for 10 on third down.
"We're realistic," Spagnuolo said. "A bunch of their guys didn't play, so it was a different competition and we've got a long way to go. We'll put it to bed and go back to work just like it's training camp."
Wide receiver Mike Sims-Walker (groin) could be doubtful for Saturday's game against the Tennessee Titans, but safety Quintin Mikell (elbow) bounced back quickly from an injury that sidelined him early, and did not need treatment on Sunday.
Several players are expected back from injuries this week, including middle linebacker James Laurinaitis (pectoral), cornerback Ron Bartell (thigh), defensive end James Hall (hip), tight end Mike Hoomanawanui and defensive end Eugene Sims (concussions) and rookie wide receiver Greg Salas (hamstring). Spagnuolo does not anticipate wide receiver Donnie Avery, coming off knee surgery, will be ready this week.
Injuries at wide receiver have made it tough for the Rams to make a solid assessment among a large group of contenders. Danny Amendola, Sims-Walker and Brandon Gibson are likely set and the team is high on rookies Austin Pettis and Salas.
Avery has been a deep threat when healthy, but missed all last season following knee surgery and has missed a lot of practice time. Danario Alexander had several big games as a deep option last year while also battling injuries.
Spagnuolo said Avery was making progress but still had pain.
"We'd like them all to be healthy," Spagnuolo said. "Certainly, the only way to evaluate them is to have them out there. Now, when that does happen guys have got to take advantage, and some guys are doing it."
Cornerback Tae Evans got playing time after being signed earlier in the day to shore up an injury-riddled position.
"You talk about getting thrown in the fire," Spagnuolo said. "That's a pretty impressive game, and a willing guy. We're a little banged-up there."