The Love Actually and Notting Hill star is part of the cast of Paddington 2, which is currently being shot in areas of the town including Bilton and Ripley.
Jim Broadbent has also been seen alongside film crews.
Facebook users claimed they had seen the A-listers in Bilton Woods and the viaduct area, while others reckoned a bungy jump stunt had been shot at Bilton Beck Bridge. They are also believed to have been spotted near the railway.
Get in touch with Harrogate reporter Finola Fitzpatrick at [email protected] if you've caught a glimpse of the actors.