Mistake in takeoff time

FlightAware AeroAPI
1

Why is it that this for this flight – http://flightaware.com/live/flight/ELY318/history/20130618/2130Z/EGLL/LLBG/times – “pushback” and “takeoff” are at the same time?

Also, this page http://flightaware.com/live/flight/ELY318/history/20130618/2130Z/EGLL/LLBG/tracklog shows that the altitude at 10:05PM UTC was 600 feet, so how can it be that that takeoff was at 9:40 PM UTC ?

Question#1: Is there a mistake here?
Question#2: If I need access to reliable takeoff times (not “pushback”) what do you suggest I do?

2

It looks like there’s a mistake here. We get takeoff times from a variety of sources with varying accuracy.

Checking against the location and altitude of the first few positions is a good idea for wheels up time verification.