IFE generally takes data from secondary, read-only busses (i.e. not integrated GPS / accelerometers, etc.). They don't provide data to any critical systems; if they did, the certification of any IFE system would be a whole lot more difficult than it currently is.
The number of aircraft flying around with anomalies in one or the other of the data types on the flight information / moving maps is an indication that deciphering the information, even once you've got a feed, is not completely trivial.
System analysis & risk assessments are performed to ensure that the likelihood of a catastrophic failure is extremely improbable.