Corrected entry: The future Chris's belt buckle switches direction in several shots when talking to future Peter and Lois.
Corrected entry: At Chris's wedding, just before the camera pans to Stewie appearing in the aisle, Francis Griffin can be seen in one of the pews. Francis, however died in the episode 'Peter's Two Dads'.
Correction: The "movie" is 3 episodes together: Season 4 episodes 28, 29, 30. 'Peter's Two Dads' was Season 5 episode 10. Francis was still alive at the end of season 4 and dies half way through season 5.
Corrected entry: Both young and old Stewie don't seem to know how human reproduction works. Yet in the episode where Peter and Lois decided to have another baby Stewie understood the biology well enough to shrink a ship and fly into Peter to destroy his sperm, implying detailed knowledge of the system.
Correction: This episode could have happened after the movie, since it isn't established where the movie fits in the timeline of the series.
The movie is divided into 3 episodes placed at the end of season 4. The episode "Emission Impossible" is S3 E11, which is before the movie.
Whether this episode occurred before or after isn't relevant because that's doesn't explain why old Stewie doesn't know if at some point his younger self knew.
Corrected entry: When Tom Tucker sits down at his "private booth" (a bathroom stall), the man who enters the stall never lifts up the seat on the toilet before sitting down, hence he sits on Tucker's food.
Correction: That's part of the joke.
Correction: For a mistake like this there must be some specifics or a timecode of when this happens. Half the movie is in the future and there is no way to verify this or see the mistake by your description.
Lummie ★