Factual error: This is a wardrobe error... in the next morning scene after William has been deflowered, he is still in his Fruit of the Looms, which have the name printed on the elastic waistband. Fruit of the Loom did not print their name on waistbands like this until the 90s, in the 70s they just had single blue and yellow stripes.
Factual error: When William runs into the street to look for Penny Lane, he runs between a row of taxi cabs. Across the street is a blue mid 90's model GMC Suburban. Since the scene takes place in 1973, this is obviously a mistake. It may be necessary to use zoom, depending on the size of your screen.