[3] McKinnon was named on the bench in Round 11 of the 2010 NRL season after prop Dan Hunt was ruled out in the warm up, however he didn't get on the field.

He signed a 3-year contract with the Newcastle Knights starting in 2012 to be closer to his family in the Hunter Valley and the fact he is originally from the area.

[4] In Round 1 of the 2012 NRL season, McKinnon made his debut for the Knights against his former team, the St George Illawarra Dragons.

After playing the first 7 rounds, McKinnon was named at second-row in the inaugural Under 20's State of Origin match for New South Wales.

While playing in the 2014 NRL season round 3 match against Melbourne at AAMI Park, on March 24, McKinnon was injured in a dangerous tackle close to half-time with Storm players Jordan McLean, Jesse Bromwich and Kenny Bromwich.

[10] The NRL's Round 19 in 2014 included a fundraising event called "Rise for Alex", with $1 for every fan attending any of the eight games donated to help him pay for his continuous medical bills and rehabilitation.

[13] In December 2016, McKinnon announced that he would sue the NRL and Melbourne Storm's Jordan McLean for compensation.