Above) By no means always, but often enough, when you cross a chihuahua with a dachshund you get jynormous ears because a dachshund has much bigger ears than a chihuahua. But the ears can stand straight up, unlike a dachsy, in the manner of a bat-eared chihuahua.
I do not know the name of the topmost chiweenie, but the one in the middle photo is Gus, a real beauty with outsized ears and a longhair chi's fur with dachshy's color. I encountered Gus, and Luigi below, on the chiweenie page of the Dog Breed Info Center.
Below) Even bigger-eared than the big-eared Gus is the chiweenie Luigi Von Hunkledink Sabo. His mom was a dachshund, his father a chihuahua, and he came out the damnedest thing, with ears almost as big as his body.
A dachsy's long floppy ears have been given a chihuahua's upright position, making him look part rabbit. He weighs only six pounds to boot. Luigi can hold his highly expressive ears straight up, straight back, or straight outward at the sides.
Luigi's owner said of him, "He is extremely intelligent, knowing how to sit, lay down, speak, beg, stand up. Knows what 'go outside, go bye-bye,' and 'go on a walk' means! I am extremely proud of him and love him with all of my heart! He is very sweet, and he loves to cuddle."