Mario Balotelli and Sergio Aguero scored penalties and Micah Richards was also on target to condemn third-placed Newcastle to their first defeat of the season and leave City as the only unbeaten side in the top flight.
City have 34 points from a possible 36 this season and have piled up a staggering goal difference of 31 to lead second-placed Manchester United by five points.
Arsenal maintained their improvement with a fifth consecutive league victory thanks to Robin van Persie's double in a 2-1 win at Norwich City.
Wigan manager Roberto Martinez labelled Blackburn's second goal "scandalous" after Rovers forward Yakubu appeared to use his hand to restart play from a corner.
"I'll make no bones about it, they are the best side we've played by some distance, very very powerful," Newcastle manager Alan Pardew told reporters.
City's goal tally after 12 games is the best in the top flight since Tottenham Hotspur netted 44 in their first dozen games in 1963 but Mancini warned against getting carried away with the idea his side will stroll to the title.
"As a team, we're strong now but we should think the season is long, probably there will be a difficult moment and for this reason it is important now if we can score goals, if we can win games in a row, it is very important," he told reporters.
Newcastle looked set to reach the break on level terms until Ryan Taylor blocked Yaya Toure's shot with his hands and Balotelli side-footed home the resulting penalty.
