What should I be looking for, when wget returns 500 but the same URL works fine in my web browser? I don't see any access_log entries that seem to be related to the error.

DEBUG output created by Wget 1.14 on linux-gnu.

<SSL negotiation info stripped out>

---request begin---
GET /survey/de/tools/clear-caches/password/<some-token> HTTP/1.1
User-Agent: Wget/1.14 (linux-gnu)
Accept: */*
Host: testing.thesurveylab.net
Connection: Keep-Alive

---request end---
HTTP request sent, awaiting response...
---response begin---
HTTP/1.0 500 Internal Server Error
Date: Wed, 12 Dec 2012 14:53:07 GMT
Server: Apache/2.2.3 (CentOS)
Set-Cookie: blueprint2-staging=8jnbmkqapl30hjkgo0u6956pd1; path=/
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Strict-Transport-Security: max-age=8640000;includeSubdomains
X-UA-Compatible: IE=Edge,chrome=1
Content-Length: 5
Connection: close
Content-Type: text/html; charset=UTF-8

---response end---
500 Internal Server Error

Stored cookie testing.thesurveylab.net -1 (ANY) / <session> <insecure> 
[expiry none] blueprint2-staging 8jnbmkqapl30hjkgo0u6956pd1
Closed 3/SSL 0x0000000001f33430
2012-12-12 15:53:07 ERROR 500: Internal Server Error.