The timeline of MoS
Was thinking about the movie's timeline. So Kal-el has been on Earth 33 years or so, meaning the Kryptonian sequence would have occurred sometime around 1980.
Next, Jor-El warns at this time that Krypton may only have a matter of weeks, and given that Lara didn't look to have aged during the planet's destruction I'm going to assumed that Krypton did indeed explode around 1980.
Well the explosion frees Zod. 33 years later he rocks up on Earth seemingly without ageing. So this gets me thinking, why is that?
1) Kryptonians are engineered so perhaps live an unnaturally long life now, therefore meaning the natural birth of Kal-El means he ages at a normal pace.
2) Krypton didn't really explode in 1980, it was much later, say 1995 and the phantom zone stopped the ageing process of Zod, coupled with the normally slower ageing of being in space explaining Zod's still relatively unchanged look.
Other than that, I'm out of ideas.