Shanahan served as Washington's offensive coordinator from 2010 to 2013, working with his father, Mike, who was the head coach at the time.
On Wednesday, Shanahan was asked what his favorite part of his time in Washington was.
"Being able to work with my dad and be around some other good coaches," Shanahan said.
And the worst part?
"Everything else," Shanahan said.
After a brief pause, Shanahan added that he did also like working with "a lot of the players." While it's clear Shanahan has not forgotten his tumultuous time in Washington, he insists there is no added motivation this week against the Redskins other than trying to get his team to its first 6-0 start since 1990.
"No, not at all," Shanahan said. "That was a while ago. I've been in three different buildings since. My dad retired. He's good. We've accepted what we had to deal with there and moved on. We'll watch other people deal with it."
Aside from an NFC East division title in 2012, Kyle Shanahan's time in Washington was mostly marked by controversy surrounding the team. The Redskins did not have a winning record in any of the other three seasons Shanahan was on staff, and Shanahan has previously made it clear that he didn't care for the how the organization was run, or the trade for and subsequent handling of quarterback Robert Griffin III, among a variety of other issues.
Shanahan told Washington-based reporters during a conference call Wednesday that he did take some valuable lessons from his time there.
"I just learned it's very important to work with people that have the same intentions and you want to go in the same direction," Shanahan said. "Football is a very tough game, and no matter how close you are with people, there's adversity that faces everyone, and when you lose one game, two games in a row, you know what's going to be written and everything, and [if] people live off that type of stuff, it's very hard to survive and get through any tough times.
"So, you've got to make sure people are made of the same stuff you are, that have the same intention, same goals and they're ready to fight and work through things and see it to the end."
Shanahan took over as Niners head coach in 2017 after serving as the Atlanta Falcons offensive coordinator the previous two seasons. Sunday's game will be the 49ers' second trip to Washington since Shanahan became head coach in San Francisco.
The 49ers lost 26-24 to Washington in Week 6 of the 2017 season at FedEx Field. This time, the Niners enter Sunday's game at 5-0 and are a 10-point favorite, while Washington is 1-5 and recently fired head coach Jay Gruden.
"I've moved on with my life in many other ways and I think my family has also," Shanahan said. "I think it's pretty easy not to make it personal -- the guys who get personal with it don't play in the game. It's not an issue; we've got our team coming to play their team and we're looking forward to that."
ESPN's John Keim contributed to this report.