Snider drove in the go-ahead run with a sacrifice fly in the eighth inning and Toronto rallied to beat the Orioles 8-7 on Wednesday.
With its 18th loss in 23 games, Baltimore fell 13 games behind Toronto and New York, guaranteeing the O's will end up in the AL East basement for the first time since 1988, when they started 0-21.
"Nobody wants to be in last place," third baseman Melvin Mora said. "Nobody wants to be a loser. It's one thing we need to turn around next year."
Scott Rolen led off the eighth with a double against Kam Mickolio (0-1) and advanced on Curtis Thigpen's sacrifice. Snider followed with a flyball to left to give Toronto an 8-7 lead.
Alex Rios hit his 15th homer and had three RBI for the Blue Jays, who finished with 14 hits. Rolen went 3-for-4 with two doubles and a triple, scored twice and drove in a run.
"This team hasn't quit at any point," Rolen said. "We got the bats going a little bit after the big inning they had, came back and hung in there."
Jesse Carlson (7-1) retired the only batter he faced to earn the win, and B.J. Ryan got three outs for his 30th save in 34 opportunities.
Aubrey Huff hit a two-run homer for Baltimore, which couldn't hold on after building a 6-0 lead. The Orioles also had 14 hits.
"It's just a tough break," manager Dave Trembley said. "You get that many hits and score that many runs and have that big of a lead and you don't win the ballgame, that's the tough part."
The Orioles scored one in the first and five in the fifth, opening the inning with six straight hits off David Purcey. Nick Markakis had an RBI double, Mora followed with a two-run single and Huff hit a 2-0 pitch into the second deck in right for his 32nd homer.
"I thought at that point I had taken us out of the game," Purcey said. "I felt like I didn't do my job as I could but credit goes to our offense."
Toronto responded with five in the bottom half. Rolen tripled home Lyle Overbay, and Snider and Marco Scutaro had RBI singles before Trembley replaced Brian Bass with reliever Lance Cormier. Rios then cut it to 6-5 with a two-run double.
"As a starter you have to go out there and minimize damage or put up a zero after a huge inning like we had," Bass said. "I didn't do it and put the momentum right back in their dugout."
Trembley said Bass "seemed to lose it all at once" after keeping the Blue Jays scoreless through the first four innings.
"Bass was throwing the ball real well," Trembley said. "He was locating pitches down, getting ahead. After we scored the five, he went out and got stuck. He pitched up and he got hit."
Joe Inglett's two-out RBI single tied it in the sixth and Rios went deep against Rocky Cherry in the seventh to give the Blue Jays the lead.
Pinch-hitter Luke Scott had an RBI single in the eighth for Baltimore.
Purcey allowed six runs and 11 hits in five innings.
Making his second major league start, Bass gave up five runs and seven hits in 4 1/3 innings.
Mora, who missed two weeks in late August and early September with a sore left hamstring, aggravated the injury fielding Thigpen's bunt in the eighth and looked slow running out a grounder in the top of the ninth. Still limping after the game, Mora said he expects to miss more time.
"It feels like it got tight," he said. "I didn't pull it, it just got tight."
Mora, who was ejected by umpire Rob Drake for arguing a called third strike in Tuesday's game, got into a discussion with Drake at third base as he was leaving the field following the first. Trembley ran out to make sure Mora didn't get ejected again, but the discussion ended quietly.
Toronto RHP Shaun Marcum will have an MRI after leaving his start Tuesday with tightness in his forearm. C Rod Barajas, who has missed the past four games with a sore hamstring, will also have an MRI on Thursday. ... Orioles RHP Daniel Cabrera won't take his next turn in the rotation, Friday at New York, and was sent him back to Baltimore to see a doctor after he complained of elbow pain during his side session. ... A male streaker jumped out of the right-field stands before the bottom of the seventh and ran across the outfield to left-center before being tackled.