When Gulliver is inviting Dan from the mail room out for a drink early in film, Gulliver has his right thumb up, pointing to himself, but in the reverse shot of Dan, he has his left thumb up.
Gulliver finds his iPhone, but although there is no signal he is still able to retrieve his voice messages.
When Gulliver first wakes on the shore of Brobdingnag, the frame is flipped with the letters of his shirt shown backwards.
At the end of the movie, when the credits are shown like a newspaper, an impossible period of time is shown: June 20 2011 - June 3 2011.