The homegrown hero latched on to Bruno Fernandes's through ball to score past Kasper Schmeichel and become the 11th Red to hit that landmark in the competition, since it was rebranded in 1992.
Rashford's half-century was brought up in his 156th league appearance, 114 of which have been starts, and, at 23 years and 56 days, he is the third-youngest player to make it to 50 for United in the Premier League era, after all-time leading goalscorer Wayne Rooney (22 years, 157 days) and Cristiano Ronaldo (22 years, 341 days).
Rashford is one of only two current players on the list, after Anthony Martial, who also notched his 50th league goal during a 2-2 draw - this one at home to Southampton towards the end of last season.