1. When {{#each}} on object, {{@last}} is undefined
2. When {{#each}} on array, {{@last}} will be true in last run
3. When {{#each}} inside another {{#each}} , {{@last}} will be set by outer {{#each}} and the behavior of 1 and 2 changed.

Sample code here:
http://jsfiddle.net/y4pd8qs2/1/