Back To The Future was probably the most accurate time travel movie. Not that it was believeable by any means, but it could happen in the fashion that was depicted. If time travel were possible, BTTF gives a very good glimpse of what could happen if you interfere with history. Only on a very small scale (in some little town where only one person's family and friends are involved). But nonetheless, mistakes that McFly made threatened his own existance. So take all that in and you could do some serious harm to mankind if you could go back in time. One little mistake could erase your existance, as well as everybody else. Or, as with the sports alminac, if the wrong people get involved with time travel that could destroy everything you know. No, time travel is not possible, but if it were, that trillogy (yeah, parts two and three were really far fetched) sheds light on what the realities could bring.