Confusion around Leeds manager Brian McDermott's position at the club continued at the end of Saturday's game when the club said he had not been sacked and remained in charge, despite the manager receiving a phone call on Friday night informing him he had been dismissed before Italian businessman Massimo Cellino had even taken control.
The 75% takeover of the Sky Bet Championship club by Cagliari owner Cellino is still subject to Football League approval.
Things looked like getting worse for Leeds when Danny Ward gave Huddersfield a deserved lead but McCormack and Jimmy Kebe soon swung the game in United's favour.
McCormack, who committed his future to Leeds and McDermott 24 hours ago amid a bid from Cardiff, then added his second and third goals before Alex Mowatt made it five.
There was controversy at Bournemouth as Kevin Phillips' controversial goal settled a 1-0 victory that moved Leicester 10 points clear at the top of the table.
Second-half substitute Phillips headed past Lee Camp with 10 minutes remaining but the furious home side were certain the whole of the ball did not cross the line.
Referee Darren Drysdale consulted with his assistant and the goal stood.
Modibo Maiga grabbed a debut goal as second-placed QPR rescued a point from a 3-3 thriller against promotion rivals Burnley.
Home debutant Kevin Doyle exchanged goals with Danny Ings before Richard Dunne fired Rangers ahead before the break.
Sam Vokes then scored twice to turn the game around until West Ham flop Maiga, who had moved to Loftus Road on loan barely 12 hours earlier, climbed off the bench to net a precious equaliser.
The scoreline was the same at St Andrew's as debutant Federico Macheda's injury-time equaliser snatched a morale-boosting point for struggling Birmingham against promotion-chasing Derby.
The Rams had only Craig Bryson's saved penalty to show for their efforts in the first half and it was the inexperienced hosts who took the lead through Brian Howard's 48th-minute header.
Derby equalised seconds later through Patrick Bamford before Chris Martin and Craig Forsyth seemed to have wrapped up the win for the visitors.
However, Chris Burke's 78th-minute strike kept City in touch before fellow substitute Macheda, signed on loan from Manchester United on Friday, stabbed home an unlikely leveller.
Wigan grabbed a sensational 2-1 victory from the jaws of defeat with two goals in the last two minutes to overcome a spirited Charlton side.
Marvin Sordell's third-minute goal had looked like giving the Addicks a lifeline at the foot of the table but substitutes Marc-Antoine Fortune and Jordi Gomez turned the game on its head by scoring goals at the death.
Pavel Pogrebnyak, Alex Pearce and Danny Williams struck the goals as free-scoring Reading inflicted a first home defeat on Millwall boss Ian Holloway with a 3-0 win.
Pogrebnyak broke the deadlock following a Stephen Bywater howler just before half-time and centre-back Pearce volleyed home Reading's second in the 72nd minute. Williams then added a third four minutes later.
Ten-man Sheffield Wednesday snatched a late winner through Chris Maguire in a South Yorkshire derby that saw three red cards.
Wednesday won 1-0 despite having Jermaine Johnson sent off, as Barnsley finished with nine men after debutants Emmanuel Frimpong and Jacob Mellis were dismissed.
David McGoldrick scored his 15th goal of the season, this time from the penalty spot following a mistake by visiting keeper Andy Lonergan, as Ipswich beat Bolton 1-0 at Portman Road to keep their play-off push on track.
Grant Hanley's first goal of the season helped secure maximum points for Blackburn from a 2-0 win over Blackpool that maintained their own assault on the play-off places.
David Dunn opened the scoring in the first half with a powerful left-footed finish from the edge of the area, and Hanley headed in a second late on.
Elsewhere, Doncaster stretched their unbeaten run to a fourth match by holding play-off hopefuls Middlesbrough to a goalless draw at the Keepmoat Stadium.