On the airplane carrying Isaac Sachs in the 1973 storyline, a newspaper is seen with the visible headlines, "PROP. 13 WINS BIG" and "Younger Wins - To Force Brown". Both California Prop. 13 and the gubernatorial race between Jerry Brown and Evelle J. Younger took place in 1978. The same newspaper appears again later, used to paper over the windows of the sweatshop where Luisa Rey and Joe Napier seek refuge from Bill Smoke.
John Gardner's "Win, Lose or Die" is seen on the 1973 bookshelf of Luisa Rey during the conversation with Joe Napier. This book was first published in 1989. The same bookshelf contains The Defector by Howard Reynolds, which was published in 1987.
The one-way "Van Ness Ave" in the film (filmed in Glasgow) does not at all look like the real Van Ness avenue (which is a wide two-way avenue, with a center divider). Nor is the Bay Bridge visible from Van Ness Ave as it is shown at one point in the film.
The goof items below may give away important plot points.
In the Timothy Cavendish "happy ending," he is writing the screenplay for the movie based on his adventures. The typewriter text shows a phrase containing the word "labored". Being English, he would most likely spell it "laboured".
In the end, two moons are shown close to each other in the sky. One of them is full, while the other is crescent. As they are close to each other and reflect the same light sources, their phases should be the same.
There are no known habitable planets from which Earth would be visible in the night sky. However, this storyline is set hundreds of years in the future, by which time a good deal of technology may exist. The "planet" in the final scene could be an asteroid or other fairly large celestial body on which Terra-forming technology is used.