 The first day that she shot a scene involving Jones the cat,  Sigourney Weaver (qv)s skin started reacting badly. Horrified,  the young actress immediately thought that she might be allergic to  cats, and that it would be easier for the production to recast her  instead of trying to find 4 more identical cats. As it transpired,  Weaver was reacting to glycerin sprayed on her skin to make her look  hot and sweaty.