The actor took his clothes off during an intimate scene with Amber Heard, and when he tried to grab what he though was her arm, he got a handful of "giant dildo" instead.
Hemsworth explained to E! News, "I get into the bed and they say 'action'. And then I turn over and I grab what I thought was (Amber's) arm, and it was a giant dildo. It was... big, a black one. And I pulled it out, and everyone was in on it... except me, yeah."
"Paranoia," centers on Adam Cassidy, a smart young executive who is fingered for corporate malfeasance and ordered to infiltrate a high-tech rival.
The film hits theaters on Aug. 16.