Castellanos, Trea Turner and Kody Clemens homered for Philadelphia (94-65), which clinched a first-round bye in the National League playoffs with their win combined with the Milwaukee Brewers' loss to the Pittsburgh Pirates.
The Phillies remain a half-game behind the Los Angeles Dodgers (94-64) in the race for the NL's top seed after the Dodgers beat the San Diego Padres 4-3 later Wednesday.
Philadelphia wrapped up its home schedule with a major league-best 54-27 home record despite impressive performances from Chicago's Isaac Paredes and Nico Hoerner. Paredes went 4-for-5 for the Cubs (81-78), while Hoerner hit a pair of home runs - his sixth and seventh of the campaign.
Check out the game summary here.
Dodgers 4, Padres 3
Shohei Ohtani drove in two runs, including a go-ahead RBI single in the sixth inning, as Los Angeles moved to the cusp of another National League West title after a victory over visiting San Diego.
Teoscar Hernandez and Gavin Lux each drove in a run as the Dodgers moved three games ahead of the Padres and reduced their magic number for their 11th division title in 12 seasons to two. The Dodgers can win the West with a victory over the Padres on Thursday.
Alex Vesia (5-4) pitched an inning to earn the win and Michael Kopech handled the ninth for his 15th save. Fernando Tatis Jr. homered for the Padres. Jeremiah Estrada (6-3) allowed a run in two-thirds of an inning.
Tigers 7, Rays 1
Spencer Torkelson homered and drove in three runs and red-hot Detroit moved closer to an American League wild-card berth with a win over visiting Tampa Bay.
Parker Meadows had three hits, including a solo homer, as Detroit won for the eighth time in nine games. Riley Greene and Dillon Dingler each added two hits and an RBI. Detroit starter Keider Montero gave up one run and four hits in 2 2/3 innings.
Tampa Bay had yielded three runs or fewer in eight consecutive games prior to Wednesday. Zack Littell gave up three runs and seven hits in 4 2/3 innings.
Blue Jays 6, Red Sox 1
Jonatan Clase collected three hits, including his first career major league home run, as Toronto defeated visiting Boston.
Alejandro Kirk added three hits and three RBIs for the Blue Jays, who ended a five-game losing streak and prevented a three-game sweep. The Red Sox had their four-game winning streak end and saw their faint playoff hopes vanish.
Toronto right-hander Kevin Gausman (14-11) allowed one run, four hits and three walks while striking out three in six innings. Boston right-hander Richard Fitts (0-1) gave up four runs, six hits and two walks with two strikeouts in five innings.
