They have their cutie marks, which in FIM happens around 7-10 in maturity (within the limits of Zipp and Pipp’s age gap), which seems in line with the MYM Chapter 5 flashbacks. They only look like FIM 5-year old here do to the TYT art style.
@Background Pony #1885
He meant that it was established that all pegasi couldn’t fly at that point in history, as established by the G5 movie. G4 established that magic is necessary for flight, but it’s G5 that established the long no-magic period in Equestria’s history.
@AdamLeisemann
The G5 movie wasn’t the one that said that the pegasi cannot fly without magic. It was G4. They are just following G4’s lore even if most of the time people think they don’t.
@Background Pony #4D6D
Well, when I was first missing, I missed that Zipp was being help aloft by one of those moon lanterns, so it looked like she was flying on her own even through pegasi could not really fly at the time (as established in the movie).
I’m sure Haven had her guards standing nearby to catch them just in case something went wrong. Still, I can see why Pipp doesn’t like the moon festival.