When Gloria arrives in Los Angeles, a Southwest airlines jet is shown landing with Heart livery (colors) which was introduced in 2014 and would not have been in service in December 2010.
After attacking Zimmerman, Thaddeus/Ennis goes back to his motel room and sits down next to the air conditioner, which has a push-button/digital control panel, a feature that would not have been available in 1975.
Ennis Stussy was 82 years old when he died in 2010, but mysteriously his character in 1975 is in his mid-20s. Thomas Mann was born in 1991, making him only 25 years old (20 years too young) when he portrayed the young Ennis Stussy.