Is this correct? Looking at the translation there is no object to be forgotten...
I think this sentence should be "Acho que esqueci ele em casa." and "Acho que esqueci ela em casa.", to include the potential object that was forgotten.
Thank you very much for your help. I have modified this sentence with your first suggestion. I invite you to add your second suggestion directly to the English sentence, if you'd like to, so you can keep the ownership.
I'll remove the tags.