The china tea set that Ella Mae and Katie drink from has flowers on it. Old Amish artwork is always abstract (generally geometric shapes), as any depiction of God's creation is considered idolatrous.
Samuel and Rebecca Lapp wear wedding rings, but the rules of Old Order Amish living (called the Ordnung) forbid personal jewelry. Samuel's beard should be the only sign of marriage between them.
Katie Lapp has buttons on her dress, which are not permitted under the rules of the Old Order Amish she grew up in.
Amish women are forbidden from wearing make-up, although both Katie and her Amish mother are obviously wearing eye make-up throughout the film and at one point in the film Katie has pale pink lipstick on while dressed in Amish garb.
Men are shown with shorter traditional English style hair cuts. Amish men have hair down covering their ears with a bowl type cut all around.
When Katie comes out of the clothing store, her hair is completely straight, when it should be wavy from being in her braided Amish hairstyle.