The play in question involved Tigers shortstop Jhonny Peralta, with a call overturned after first-base umpire Jeff Kellogg conferred briefly with home-plate umpire Tim Timmons.
"It's embarrassing that they would overturn a call that obviously has an impact on the game in the middle of the pennant race," said Reynolds, who was ruled to have his foot off the bag despite video replays showing he maintained contact.
"I've never in my life seen someone reverse a call," said Reynolds, who was ejected by second-base umpire Vic Carapazza after spiking his glove into the dirt in anger.
"This game is way too important right now, where we are in the season, for these kinds of calls to happen. And it's very frustrating."
The play started with a great stop from rookie third baseman Manny Machado, who made a backhanded stab at the ball, pivoted and threw across the diamond to Reynolds on a short hop. But the throw was offline and Reynolds stretched to retrieve it, laying out fully. He maintained that his foot was still in contact with the bag, and the initial ruling by Kellogg at first base had Peralta out.
As Peralta started yelling to contradict the call, Timmons came up to speak with Kellogg.
"From when I saw the throw coming across, I knew that the throw was going to pull the first baseman that way," Timmons said. "And at that point, that's when I actually stopped and dropped anchor and looked for the foot. And when I saw the foot come up, the heel and the toe [were] on the bag. ... At the time he was going to glove the ball, when I saw the bottom of the whole foot and the foot dropped down onto the ground and I had daylight, I had him off the bag."
"We just want to get the play right, and that's what we did there," Kellogg said.
As to why he originally looked to Timmons, "The runner said something, the first-base coach said something, [Tigers manager Jim] Leyland came out there."
And then so did Showalter, who pushed aside starter Tommy Hunter -- who had gotten in on the yelling action -- and got in the umpires' faces, turning bright red and animatedly stating his case before being tossed as well.
"I was shocked," Showalter said. "Especially with as good a play that Mark had made. Manny made a great play on it, too."
"A couple of the guys from the team said they saw the replay on TV and they said it was out," Peralta admitted. "If it's close, to me, that means safe."
It was Reynolds' second career ejection, his first as an Oriole, and Showalter's 24th and second of the season. Friday's calls -- including one in the first inning, when Nick Markakis was thrown out at home, a play Showalter also disputes -- left a bad taste in the Orioles' clubhouse as the team is fighting for a postseason berth.
"It's almost like, ['Let's mess with] the Orioles' by the umpires," Reynolds said. "I mean, [Adam Jones] was obviously safe at first base the other day, cost us a run against Boston. There's got to be some kind of replay for this. It's to the point where all these calls that get missed cost people runs, cost people outs. Cost [Hunter] extra pitches. I can't say how I really feel, but it's pretty obvious."
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.