When Bernard Lefkowitz is arguing with the other about visiting the "lifepool", he states that Dutch Shultz visited his store in 1948. Dutch Shultz was shot and killed in his makeshift headquarters in 1935.
When the four men are hiding in the pool closet and the Anterians come into to put the day's haul of cocoons into the pool, the tile floor is completely dry, though the men had just exited the pool moments before, dripping wet.
When the old folks all invade the pool house, there is a fellow on the deck of the pool trying to crack open the cocoon. A few seconds earlier, that same fellow is in the middle of the pool when Walter catches everyone. The fellow is subsequently in two places at the same time.
When Wilford Brimley and Maureen Stapleton are driving in the Cadillac and Brimley asks Stapleton if she has second thoughts about the trip into outer space, you can see the AAA sticker on the rear view mirror is upside down.