Ronaldo's first 15 Champions League goals came for United – including a towering header in the victorious 2008 final against Chelsea in Moscow – before he joined Madrid in 2009 for what was then a world-record fee of €94million.
The 32-year-old has gone on to win the trophy on two further occasions, and Carrick is amazed that he has reached such a milestone.
"It's verging on ridiculous, really, to score so many goals in such a challenging competition," he told United's official website. "It really is incredible.
"I watched both games against Bayern. He gets a sniff of a chance and 'bang', it's away. There weren't really many other chances that he squandered. He had a few shots but you almost bank on him to score.
"It's a frightening, frightening stat. But how many records has he broken over the years? It's unbelievable and tells you everything about him."