The Hunger Games takes place 300-500 years from now, so they have the ability to create mutations (like Craker Jackers and Jabber Jays). They are not made out of thin air.
The other districts dress retro because they are very poor and starving. Catastophic events (nationwide fires, rising sea levels, etc) occurred in the past which left them without cell phones, satellites, etc. Katniss lives in what was once Appalachia.
Secretariat was poorly done! I am a big horse racing fan--Penny Chenery was not there when Secretariat was born, nor was Lucien Laurin. There was no battle between Secretariat's connections and those of Sham's --Pancho Martin. I was watching it and shaking my head.
Secretariat won the Belmont by 31 lenths but the film failed to capture the excitement and glory.