"Sometimes we like players others don't like", Mourinho continued.
It wasn't until the 86th minute that Lukaku managed to finally score a goal, sealing the match for United at 4-0.
This is the first time that Marcus Rashford has assisted two goals in a single game for @ManUtd. That record is now extended to seven matches.
Unbeaten United led within three minutes when Marcus Rashford's excellent work on the left wing ended with a cut-back to Juan Mata, who steered home from 10 yards out.
A quiet spell followed the early drama, with the next shot on target for either side not coming until after the half-hour mark when David de Gea beat away an effort from Bakary Sako, who was starting in an unfamiliar striking role with Christian Benteke out injured.
Without hitting top gear, United doubled their advantage in the 35th after the industrious Ashley Young delivered a flawless cross from the left for Fellaini to sweep home at the far post.
Having struck early in the first half, United repeated the trick within four minutes of the restart.
He's done it again! The ball is easily struck by my Lukaku. Intelligent breakthrough bait from Herrera forwarded Martial through his crossing into the goal mouth.
Fellaini's double was sandwiched between Juan Mata and Romelu Lukaku goals in a comprehensive 4-0 win that saw United equal their record tally of 19 points after seven Premier League matches as embattled Palace fell to another loss.
"We've created a lot of chances, scored goals, and we need to keep that level".
- Only Halifax Town in 1990-91 (730 minutes) have gone on a longer run from the start of a season in English league history (top four tiers) without a goal than Crystal Palace this season (630 mins). Conversely, this is the seventh defeat for Palace, who are now at the bottom of the table. The only game he's failed to score in so far this season was against Leicester, when he had a penalty saved.
Some may see Palace as an easy return to domestic action given they have suffered the worst start ever to a Premier League campaign.
Asked about his thoughts on playing in Russian Federation and then preparing for a Premier League match, he added: "I had concerns".