Holland explained Tuesday how his intention wasn't to ghost his Avengers co-star but that he ignored the call due to receiving it late at night while in London.
"I woke up and panicked. I was like 'Oh my god! I'm so sorry! I didn't mean to ghost you,'" Holland said about what he texted Downey -- who is named The Godfather-- inside his phone.
"He obviously didn't reply for ages because of the time difference in L.A.," Holland continued about the ordeal. "So that was maybe the most stressful day of my life where I thought my relationship with Downey was over."
Holland also recounted how he was recognized by a fan while attempting to help a fellow passenger on a flight to Hawaii.
The actor said he helped a woman who had fainted near him when a passenger recognized him due to watching Spider-Man: Homecoming on the plane.
"She must have thought 'Wow this kid just never stops!'" Holland joked about the passengers reaction.
Holland will be seen as Spider-Man once again in Spider-Man: Far From Home, which arrives in theaters on July 2.