After seven league matches, United remain unbeaten in the league.
Samuel Luckhurst of the Manchester Evening News shared the teamsheet, and he complained about the official before the first ball had been kicked:
It took the Red Devils just three minutes to take the lead, as Marcus Rashford created space and moved past Joel Ward before playing the perfect assist for Mata.
Luckhurst loved what he saw from the youngster:
Mamadou Sakho came close to pulling his side level minutes later, but his header went off target.
United's fast start didn't last, and the hosts took their foot off the gas after taking the lead. While the Eagles barely threatened David De Gea, chances were rare on the other side of the pitch as well.
Bakary Sako drew a fine stop from the Spaniard with a shot at the near post, but Palace's lack of creativity in the first half remained a problem.
BBC Sport's Simon Stone highlighted their struggles with this statistic:
With 10 minutes left to play in the half, Ashley Young fired a perfect cross into the box, and Fellaini doubled his team's advantage.
And the hosts had several late chances to add a third goal, with Chris Smalling heading wide, Rashford hitting the post and Henrikh Mkhitaryan blasting over.
At half-time, sports writer Karl Matchett was disappointed with the visitors:
Similar to their fast start in the first half, United came out on the attack in the second, scoring early. Rashford fired an excellent cross into the box from a free-kick, and Fellaini did what he does best, powering home a strong header.
Sports writer David Amoyal noted manager Jose Mourinho's effectiveness:
Lukaku could have added a fourth goal if his touch didn't let him down, and Jeffrey Schlupp failed to threaten De Gea with a header. Jairo Riedewald perhaps should have ended Palace's scoreless streak with a volley from inside the box, but he failed to keep his effort on target.
Anthony Martial had a late chance before Lukaku put a fourth goal on the board after lovely work from the Frenchman in the buildup.