It's the Easter Beagle, Charlie Brown(1974)

Synopsis

Charlie Brown, Linus and the entire Peanuts gang are off on a lively Easter egg hunt. They suspect they've spotted the Easter Bunny … but the trouble is, he looks a lot like a certain beagle who's near and dear to Charlie Brown's heart. Is it truly the Easter Bunny, or is it just the irrepressible Snoopy playing a trick on the kids?