Twin Paradox and how "Contact" got it wrong

Twin Paradox in "Contact"

Contact is a 90s since fiction movie that explores the idea of intergalactic space travel and what would happen if we ever to get contact with intelligent life.  The movie follows astronomers trying to track a signal from the other side of space. At the last moment before funding ended they get a signal in which aliens sent them to hear. They are sent instructions on how to build a machine which would send a 1 human to make contact with them. It involves this massive spherical mechanism with rings that speed up and then a person is dropped into the center of it. 

The machine sends the main character through a series of wormholes as she passes into the center. After she speaks with this intelligence of who left basically no information about who they are and what they want, they send her back to Earth. She goes through 18 hours of travel and makes it back to Earth unharmed somehow. But from the people on Earth's perspective she passes right through the machine in a second and lands in the water below. They are very confused because to them it seemed nothing happened but she went to the other side of the Universe in a very rapid manner. In this case she is 18 hours older than everyone else on Earth which is incorrect in the physics of relativity. If it were accurate she would have been gone for 18 hours while she would have only experienced 1 second of it. This is because of time dilation which accounts for the change in acceleration. The faster an object moves through space, the slower it moves through time compared to an unmoving observer. Therefore, she would have came back older without her noticing much change. For this to be fixed in the movie I think they could have simply had her disappear as she went through the machine as some sort of portal(its already pretty far-fetched so why not add a little more) for a certain amount of time and reappear later. I don't think this would have made the movie less enjoyable to watch simply because it seemed like all the effort was for nothing since there was no evidence and it seemed like she just hallucinated.

Overall I actually really enjoyed this movie. Besides some things in the movie seeming very pointless and ridiculous, it is one of the most interesting and unique films i've ever seen. I give it a PGP-13 because it portrays many things very accurately but also goes pretty far into the realm of make-believe.