Continuity mistake: In the shots of Scrat getting flung away after tripping and then bouncing between the inner and outer core, the distances between the inner end of the outer core and the inner core are completely different. (00:02:10)
Continuity mistake: In the shot when Granny talks about her dead pet and the young male sloth complains about it, the uncle sloth can not be seen between them, but instead appears between them in the following shot. (00:05:25)
Continuity mistake: Fleeing from the giant crab, Sid runs to the leading edge of the huge ice float. Two shots later, the camera displays the leading edge of the ice float as it begins to go downhill, but Sid isn't there anymore. (00:18:00)
Continuity mistake: When the pirates sing their shanty they throw sea stars at Sid on each side of him. In different shots, there are three on one side. (00:29:40 - 00:30:40)
Continuity mistake: When Sid and Manny are chasing the boat, Manny lifts up Sid and he is hit by a branch. However, in the next shot the branch is gone. (00:52:15)
Continuity mistake: When Scrat arrives at Scratlantis, it is shown that the acorn-shaped island is formed by 3 land masses lined up. However, when Scrat causes the island to sink, a full solid acorn-shaped island is shown sinking. (01:17:00 - 01:18:50)
Answer: It's probably just a very similar one.