In a video posted by TMZ, the 80-year-old actor is seen in a wheelchair while on stage at Shea's Performing Arts Center in Buffalo, New York, for a conversation after a screening of the classic holiday film.
Chase is later seen standing up and walking toward the other side of the stage to wave to the audience, when he appears to stumble and disappear off camera to gasps from the crowd.
The “Saturday Night Live” alum was then helped back up onstage by the Q&A interviewer and Chase's wife, Jayni Chase.
"Wait, wait my watch is talking to me," Chase said after returning to his seat. He then raised his smartwatch to his face. "It says, 'I see you've taken a great fall.'"
The audience began to laugh, with Jayni Chase poking fun at the minor fall while appearing to try and fix the watch. "Otherwise, they might send an ambulance," she said, placing her hand over her face as she started to laugh.
USA TODAY has reached out to a rep for Chevy Chase for comment.
Chase starred as Clark Griswold in 1989's "National Lampoon's Christmas Vacation," the third installment in the film series. Centered on the Griswold family, the holiday installment sees Clark Griswold attempt to throw the perfect holiday for his family, with plans soon going off the rails.
Chase kicked off the film franchise in the original 1983 film, "National Lampoon’s Vacation" opposite Beverly D'Angelo as Ellen Griswold, as well as the four additional full-length films and a 2010 short film, "Hotel Hell Vacation." A 2003 spinoff, "National Lampoon's Christmas Vacation 2" featured a new cast of characters without Chase and D'Angelo.
'National Lampoon's Christmas Vacation' streaming info, TV airtimes, cast
This article originally appeared on USA TODAY: Chevy Chase falls off stage at 'National Lampoon' movie screening