The marching band drummer, while standing in front of the grandstand.
Peter and Alice, invited to attend the charity event, can be seen sitting at their table at the party before they even entered the room.
The Polaroid which terry examines with a magnifying glass shows Peter smiling slightly. The picture Alice & Janice look at has his mouth closed in a grimace (the plot makes an issue of why he isn't smiling in the photo).
In the final scene, when the helicopter is returning from the retrieval mission, Meg walks up to greet her husband, and she has a huge fever blister on the right side of her upper lip. Later, in that same scene, the fever blister disappears.
Incorrectly regarded as goofs
The grenade Dino throws into the hut is a noise/flash distraction device, commonly called a "flashbang." Flashbang grenades do not detonate and fragment like antipersonnel grenades, so it would be normal to see the spent grenade body lying on the floor.
Even though the movie takes place in a fictional South American country, the Ecuadorian flag can be seen flying in many places.
Bowman speaks into the wrong side of his Nokia 9110 Communicator.
When two ELT soldiers fly into the air after Thorne detonates a claymore mine, wires are visible aiding the stuntmen.