Continuity mistake: On the ferry, Rachel wears the purple/pink camouflage hoodie OVER her orange knit sweater with the colorful stripe sleeves, as usual. Now this is where things become strange. In the first shot as the trio come ashore, she is only wearing her orange sweater, she is not wearing the purple/pink hoodie note the clear lack of fur hood. In the very next shot as they climb a bit more and then rest, Rachel is wearing the purple/pink hoodie note the hood, but now it's on UNDER her orange sweater. In the underwater shots she is also wearing it under the orange sweater. (This odd mistake has absolutely nothing to do with the very long wool cloak that Rachel wears in the next scene.)
Continuity mistake: When the ferry casts off in the wideshot, there are only six people hanging off the outer edge of the ramp as it's being raised. When Robbie and another gentleman help these people over, in the close-up one of them wears tan pants, a long blue coat and knit hat, but this person was not amongst the six in the previous shot.
Continuity mistake: When Ray and the kids are hiding out in the mom's basement, they take cover in a small utility room that goes pitch black when Ray shuts the door - even though there are windows above the girl's head that emit light before he shuts the door and after he opens it to leave.
Other mistake: When Ray pulls up to Mary Ann's home, the front exterior layout and dimensions of the house are evident, from its near center front door to the two car garage, in front of Ray's van. The side exterior wall contains two large garage doors, which are about 35-40 ft from the location of the front door, with no small basement windows at ground level; inside, beside the front door, the stairs that lead to the basement run parallel just under the stairs in the foyer. In the basement, the small windows on the far end of the furnace room they run into are only about 20 ft from the basement stairs. Not only are the small windows non-existent in the exterior shot, but it's entirely impossible for two small windows to be where they are, considering the exterior footage of the house.
Visible crew/equipment: In Mary Ann's kitchen, just as Ray comments, "Ok, well you hungry? I'll get you some food," the clear reflection of a male crewmember moving around is visible in the glass window behind Ray. Then just as he says, "This is ketchup and mustard," another older male crewmember is visible directly in front of Rachel's reflection.
Continuity mistake: When the van is parked at the side of the road, as Rachel heads off Ray shouts, "Every time you guys don't listen to me I'm telling your mother..." In the next shot the van is seen quite a distance away as Rachel reaches the shoreline. After seeing the floating bodies Ray picks her up, turns around and as he begins to run the van is seen, only this time is much, much closer. Ray never moved the van, as shown in the following shots.
Continuity mistake: In the exterior shot of Mary Ann's house, there are three large windows of the same size over the front door, and large bay widows on both sides of the door. In the interior shot, when Ray remarks, "They're never here," the window over the door is visible and it is one large center window with very small windows on each side. In the dining room there are two windows with wall in between, certainly not a large bay window. (Additionally, in the living room there is a fireplace, where there were two windows in the exterior shot - but some could say that those windows were boarded up and a fireplace was built in front of it.)
Continuity mistake: In Mary Ann's basement, when Ray and Robbie are looking out the small window, as the aliens begin their attack, Rachel runs over and Robbie hugs her tightly. However, in the next shot of Robbie and Ray, Rachel is gone, yet in the very next close-up Robbie is still hugging Rachel. (The shot of Ray and Robbie without Rachel is cut from a previous shot, before she runs to them.)
Continuity mistake: When Ray parks the van at the side of the road, the van is about 60-70 ft away from the tall wood post, at the road intersection up ahead. However, in the first shot of the military vehicles approaching, the van is parked directly in front of that wood post at the intersection, and this also occurs in the shot as Ray shouts, "Robbie! You wanna go in that direction?"
Revealing mistake: When the Hudson Ferry captain casts off the large label that reads "Hudson Ferry" is on his left side of his jacket. However, in the exterior shot as he looks out the window at the whirlpool, the label is on his right side. This shot was flipped, and amusingly, the CGI guys actually retouched the words "Hudson Ferry" so it wouldn't read backwards.
Continuity mistake: As Ray speeds away when Manny's shop blows up, Robbie shouts, "Holy s**t!!" and ducks. The rearview mirror on the van's windshield, in this close-up, is entirely different to the one seen a few shots later, when they're on the freeway. The mirror changes yet again later.
Continuity mistake: In the interior shot, the Hudson Ferry captain walks toward and then stands at the doorway (seen clearly when he cast off earlier), as he stares at the growing whirlpool. However, in the next exterior shot he is standing at an open porthole window, staring at the water.
Continuity mistake: When Ray, Robbie and Rachel arrive at Mary Ann's house, as the kids shout for their mom and Tim, the door to the basement under the stairs, as well as the den further up (beside the kitchen), are all perfectly visible. Later, after the house is destroyed, when Ray walks through the basement doorway, the walls, moldings, and so on are entirely different, and now there is an extra wall (perpendicular to the camera) to the left (viewer's) where there was none before.
Continuity mistake: When Ray empties the bag of bread, nine of its slices fall out, and he drops the plastic bag (the rest don't fall out). In the next shot there are seven slices total (not nine), and Ray tosses one of them near the box, since he needs only six. But a few shots later two slices appear near the box, together with the six that Ray uses to prepare for sandwiches, totaling eight.