Rizzo and Castro each struck out on foul tips vs. A's lefty closer Sean Doolittle in the top of the eighth for the National League during the American League's 5-3 win.
Castro, who replaced starter Troy Tulowitzki in the bottom of the sixth, struck out on a 95 mph fastball. On a 1-2 count as he pinch-hit for Giancarlo Stanton two batters later, Rizzo fanned on a 94 mph fastball from Doolittle.
Rizzo -- the NL Final Vote winner to get into the Midsummer Classic for the first time -- was elated by his All-Star experience before he even took the field.
"It's been awesome," Rizzo said. "I'm really happy to have been able to do this and have my family here to join me. They've helped me so much along the way. I'm just soaking it all in."
What was his favorite part of the festivities?
"I enjoyed the [Gillette Home Run Derby] and watching the guys hit, but the parade was awesome," Rizzo said of the Tuesday afternoon red carpet parade downtown. "There were so many fans that came out here. They've been really nice. It's been an experience I will never forget."
If nothing else, Rizzo was also able to mend fences with a foe-turned-temporary-teammate in Reds closer Aroldis Chapman. There were no issues when the two crossed paths for the first time since Rizzo sparked a benches-clearing incident on Thursday. In that game, he yelled at Chapman and approached the Reds' dugout for throwing inside to teammate Nate Schierholtz.
"I don't have a problem. There is no problem," Chapman said of Rizzo before the game and noted that they shook hands.
"We said hello," Rizzo said. "I don't see why there would be anything else other than that. It's something where it was the fifth game in four days, and a hot day. I talked to all of them -- [Alfredo] Simon, [Johnny] Cueto [and Todd] Frazier. I was pulling for Frazier in the Derby. They're great guys, they really are."
Castro was back on the NL squad for the third time in four seasons, after he was absent in 2013 amid his most disappointing year in the Majors.
"It's really good for me, especially after the kind of year I had last year," Castro said of being back in an All-Star Game. "It's helped me a lot with my confidence. Last year, I really struggled. This has been a new year. I'm happy to get to be here again. It's been fun."
Castro, who is now 0-for-3 in All-Star Games, is hitting .276 with 11 home runs and 52 RBIs this season and already surpassed last year's production totals of 10 homers and 44 RBIs with a .245 average in 161 games.
"I have a strong mind right now," Castro said. "I don't think anything can pull me down. I trust myself. I think I have my confidence back."