Can you fatally overdose on your haldol (haloperidol)?

Unfortunately Yes: Overdosage of Haldol (haloperidol) is manifested by many of the same side effects experienced only to an intense degree: severe extrapyramical reactions (tremor, rigid muscles, weak muscles), low blood pressure, and sedation. One can experience severe cardiac problems leading to cardiac arrest. Since there is no antidote, supportive treatment is all that is available. So know your dose and follow it closely.