When Mitchell and Claire are in the park and Mitchell says that he never loved figure skating, the position of Claire's arms constantly change between shots, without her moving.
When Jay and Gloria are prepping Manny for his fencing match, Manny's grip changes back and forth between shots.
While at the fencing meet, Mitch is carrying what is supposed to be Lily in a baby carrier on his chest. It is actually and noticeably a very unlifelike doll.