Disassemblers are crucial in the analysis and modification of binaries. Existing works showing disassembler errors largely rely on practical implementation without specific guarantees and assume source code and compiler toolchains to evaluate ground truth. However, the assumption of source code is contrary to typical binary scenarios where only the binary is available. In this work, we investigate an approach with minimal assumptions and a sound approach to disassembly error evaluation that does not require source code. Any source code does not address the fundamental problem of binary disassembly and fails when only the binary exists. As far as we know, this is the first work to evaluate disassembly errors using only the binary. We propose TraceBin, which uses dynamic execution to find disassembly errors. TraceBin targets the use case where the disassembly is used in an automated fashion for security tasks on a target binary, such as static binary instrumentation, binary hardening, automated code repair, and so on, which may be affected by disassembly errors. Discovering disassembly errors in the target binary aids in reducing problems caused by such errors. Furthermore, we are not aware of existing approaches that can evaluate errors given only a target binary, as they require source code. Our evaluation shows TraceBin finds: (i) errors consistent with existing studies even without source; (ii) disassembly errors due to control flow; (iii) new interesting errors; (iv) errors in non-C/C++ binaries; (v) errors in closed-source binaries; and (vi) show that disassembly errors can have significant security implications. Overall, our experimental results show that TraceBin finds many errors in existing popular disassemblers. It is also helpful in automated security tasks on (closed source) binaries relying on disassemblers.