Towards the end, Larry alerts Moe and Shemp that the judge is at the party, the one who "wants to send us up for life." At no point in the courtroom sequence does the judge say or imply that.
What looks to be a watch falls from Mrs. Henderson's wrist as the birthday cake is rolled out at the end.
During the sequence with Shemp and the turkey, his constant ad-libbing and the pounding of the turkey causes someone to laugh off-screen.
When Moe hits Shemp and Larry on the head with a stick of wood, Larry hold his hand in pain, for no apparent reason.
After Shemp sprays Moe in the face with cake icing, he and Larry jump in shock, but the cake doesn't float up like it is supposed to.
When the chicken flies out of Shemp's coat, you can see a shadow of the hand pulling the wire.
The wire holding the floating cake can be seen on its top.