The game took place at United's Carrington training ground, with the aim to give stars who are lacking match sharpness the chance to gain valuable minutes before the season begins.
The Manchester Evening News reports both defender Lisandro Martinez, who has signed from Ajax, and former Brentford midfielder Christian Eriksen made their unofficial debuts for their new club.
The report adds Eriksen scored the opener for United, before Wrexham defender Aaron Hayden equalised just before half-time.
Erik ten Hag's side then netted three times, with Alejandro, Amad Diallo and Alex Telles getting on the score sheet after the break without reply.
It is also understood Ronaldo was in attendance to watch the match from the sidelines, but played no part, as speculation continues to over his future at the club.
The 37-year-old had previously been absent, citing personal reasons, but returned for talks with manager Ten Hag on Monday.
It is believed Sir Alex Ferguson, who was attending a board meeting with Bryan Robson on Tuesday, also held a brief discussion with him.
Bruno Fernandes, Marcus Rashford and Harry Maguire are also understood to have watched on alongside the Portugal international.
United face Diego Simeone's Atletico Madrid in their next pre-season clash on Saturday July 30 in Oslo at the Ullevaal Stadion.
They then return for Ten Hag's first game at Old Trafford a day later against Rayo Vallecano, before their season gets underway a week later at home to Brighton.