The away team threatened early on but could not recover from losing Triguero and Baena in the first half-hour, and the game quickly turned into a training exercise for the hosts
Sections of the home support whistled under-fire manager Rafael Benitez before kick-off and his players received similar treatment at half-time despite being 4-2 to the good against depleted opponents.
Gareth Bale turned a first-half brace into a four-goal haul, quelling the early discontent that had long subsided by the time Karim Benzema completed a hat-trick in the final minute.
Danilo gave Madrid a third-minute lead but quickfire efforts from Antonio Amaya and Jozabed had neighbouring Rayo dreaming of a famous triumph.
Those ambitions were undermined when Tito hacked into Toni Kroos to be sent off and, after Bale equalised, Raul Baena also received his marching orders – preceding a successful penalty from Cristiano Ronaldo.
Benzema opened and closed the second-half mauling, while Ronaldo headed a second and Bale made hay.
Madrid are now within two points of champions Barcelona, who wrapped up Club World Cup glory in Japan earlier on Sunday, but the bizarre nature of this rout is unlikely to bring many Benitez doubters onside.
The carnage was far from over and Rayo were down to nine men in the 28th minute as referee Ignacio Iglesias Villanueva gave Baena a second yellow card for tangling with Sergio Ramos inside the area.
Paco's team were understandably aggrieved as Ronaldo coolly drilled home the resulting penalty.
James sent Bale streaking through the undermanned Rayo ranks to double his tally and the same combination almost heralded a first-half hat-trick in stoppage time, but the ex-Tottenham man could not convert at the far post.
The utterly surreal feel to proceedings was heightened when Real were whistled at half-time and they sought to repair these fractured relations with their fans as Benzema slotted home number five, James the provider once more.
Yoel was out sharply to deny Ronaldo in the 50th minute but his was a thankless task and there was nothing he could do when the Portuguese superstar firmly nodded James' left-wing cross into the net.
Rayo attacked when possible, left-back Nacho having a venomous shot blocked, heralding the unlikely sight of nine men conceding their seventh on the break after 61 minutes.
James released Ronaldo to leave Bale with a simple finish for the matchball and he had a fourth when an attempted nutmeg on substitute Quini fell favourably.
Luka Modric found an unmarked Benzema to dispatch number nine and there would be a second hat-trick when he thumped in a lay-off from substitute Mateo Kovacic left footed - concluding a scarcely credible contest in the Spanish capital.
CORRUPTION SCRIPT (brought to you buy Coke Zero):
PEREZ: Hey ref (inserts money in refs pocket), I need to make my princess happy. He is falling behind in the scoring charts.
REF: What you want? 2, 3?
PEREZ: I'd like to order 2 red cards, Princess will manage to score then, i think...
REF: Sit back and relax, purchase is confirmed
-------AFTER THE MATCH-----------------------
PEREZ: So, Ronaldo, do you really want to leave now?
PRINCESS: Bale is scoring more than me again...
PEREZ: Mhmmmmm....(sells Bale)
PRINCESS: Benzema too...
PEREZ: ...(sells benzema)...
PRINCESS: ...I want to be the highest paid footballer...
PEREZ: (angrly mumbles)...We'll see about that (sells the other stars Modric & James...)
PRINCESS: Ti amo papi (love you father)