Marler temporarily stepped into the breach at Murrayfield when Luke Cowan-Dickie was sin-binned for a deliberate knock-on, taking the hooker's role on the touchline in the 69th minute when the score was tied at 17-17.
However, the veteran prop's botched throw to Alex Dombrandt failed to travel five metres and, as a result, England gave up a scrum close to their line which was then penalised, allowing Finn Russell to land the match-winning penalty.
It was an influential chain of events in a final quarter that was poorly managed by England and Marler accepts his role in the unravelling.
"I've been practising every day. Cockers (forwards coach Richard Cockerill) has been giving me the eyes - 'right, any danger this week mate?'. I was like 'yes, OK, fine," Marler said.
"I just didn't throw it at the right time. I should have thrown it earlier at Dombrandt. Unfortunately I threw it later and he kept running past the five metres with the eyes of 'mate, why are you not throwing the ball at me?'.
"And I went 'I don't know, I feel like Eminem in 8 Mile when he chokes on stage with his rap'. That's how I've felt.
"Unfortunately, my international record at throwing in is now down to 50 per cent because it was at 100 per cent.
"In my third ever Test, against South Africa away in 2012, Dylan Hartley got sin-binned, I threw it to Geoff Parling in the pod, he won the ball and I had a 100 per cent throw in record. Unfortunately it's now down to 50 per cent.
"I was very disappointed with losing as closely as we did. It was disappointing and I don't feel overly great about it, but I'm looking forward to tucking in this week and hopefully picking up the learnings of that last 20 minutes at Murrayfield."
Marler endured his second dose of Covid in less than three months when he tested positive during last month's Brighton training camp, but the loosehead was able to resume training before England departed for Edinburgh.
"I didn't get away with any mid-afternoon naps in my house. My missus took it as an opportunity that 'you're home now, cool, there's baby one and there's baby two'," said Marler, a second-half replacement at Murrayfield.
"The first time I struggled and I probably underestimated it back in the autumn. My chest was struggling for a while after that, but this time back in Brighton I think that from the testing it might have been the Omicron variant. It's well know that it's milder and I didn't suffer as much."
England will aim to revive their Six Nations title quest against Italy in Rome on Sunday and Marler knows what awaits at the Stadio Olimpico.
"Passion, passion, passion. Italy are a very proud nation. They're kicking really well, their set-piece is strong. I'm expecting them to come out firing for that first 20 minutes at home," Marler said.