The ladies playing the museum visitors, were not told that Christopher Walken was going to interrupt the docent's explanation of "The Lonely Maiden". Therefore, their reactions to Roger's expertise were genuine.
In the script, the scene of George first stowing away in the crate, ended where he gets back out of it. The remainder of the scene was ad-libbed by William H. Macy and Christopher Walken. Walken does indeed have arthritis in his hands.
Roger (Christopher Walken) and George (William H. Macy) try to lift a crate using a shovel as leverage. William H. Macy played a character called Shoveler, who uses a shovel as a weapon in Mystery Men (1999).