Considering her role in that film, we’re not so sure that’s what’s happening here, unless there’s a particularly inspired sequence where Hayley Atwell turns into either a Heffalump or Woozle in a hallucination suffered by her on-screen husband.
But, stranger things have happened, so we won’t totally count this theory out.
There is a distinct possibility that this new photo Atwell has shared, describing her “process”, could be part of her work on Christopher Robin, the live-action film where she will play wife to Ewan McGregor’s all grown up protagonist from A.A. Milne’s Winnie The Pooh series.