1. Smalltalk has first class, live activation records (instances of the class Context). Smalltalk offers the special "variable" thisContext to obtain the current stack frame at any point during method execution.
If an exception raised, the current execution context is suspended and control is transferred to the nearest exception handler, but the entire stack frame remains intact and execution can be resumed at any point or even altered (continuations and prolog like backtracking facilities have been added to Smalltalk without changing the language or the VM).
2. The exception system is implemented in Smalltalk itself. There are no reserved keywords for handling or raising exceptions. The implementation can be studied in the live system and, with some precautions, changed while the entire system it is running.
3. The Smalltalk debugger is not only a tool for diagnosing and fixing errors, it also designed as tool for writing code (or put differently, revising conversational content without having to restart the entire conversation including its state). Few systems offer that workflow out of the box, which brings me to the last point.
4. I said earlier that Racket is different from Common Lisp. It's not only about language syntax, semantics, its implementation or other technicalities. It is also about the culture of a language, its history, its people, how they use a language and ultimately, how they approach and do computing. Even in the same language family tree you will find that there are vast differences, if you take said factors into account, so it might be worthwhile to study Common Lisp with an open mind and how it actually feels in use.