The 48-time capped Scotland forward is out of contract with Well but is close to agreeing a new deal, and appeared against Alan Pardew's men as a second-half trialist.
By the time of his arrival, however, his team were already behind to goals from Haris Vuckic, Yoan Gouffran and Moussa Sissoko, with just Iain Vigurs' opportunistic strike to show for their first-half efforts.
McFadden soon reduced the deficit with a clever penalty but the youthful Magpies outfit again showed their class with a fourth from substitute Sylvain Marveaux as they wrapped up a comfortable win.
West Ham continued their pre-season campaign with a 2-1 win over League One Colchester at the Weston Homes Community Stadium.
Joe Cole and defender James Collins were on target at the start of each half for the Barclays Premier League side before substitute Jabo Ibehre headed in a stoppage-time consolation with a powerful header.
Elsewhere, Reading drew 1-1 against Portuguese side Belenenses. The Royals went a goal down after the home side scored a first-half penalty but Adam Le Fondre levelled the scores with his second goal in as many games in pre-season.
Blackburn beat Crewe in their match at Gresty Road thanks to Grant Hanley's early header.
Hanley powerfully headed home Ruben Rochina's corner in the 11th minute to seal the win.
Meanwhile, Nottingham Forest played out a 1-1 draw with Chesterfield. Matt Derbyshire opened the scoring for Forest in the 17th minute when he raced on to a perfectly weighted through ball from Andy Reid, but his score was cancelled out by Gary Roberts'second-half strike for the Spireites.